CA2493212A1 - Method for locally highly resolved, mass-spectroscopic characterization of surfaces using scanning probe technology - Google Patents
Method for locally highly resolved, mass-spectroscopic characterization of surfaces using scanning probe technology Download PDFInfo
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- CA2493212A1 CA2493212A1 CA002493212A CA2493212A CA2493212A1 CA 2493212 A1 CA2493212 A1 CA 2493212A1 CA 002493212 A CA002493212 A CA 002493212A CA 2493212 A CA2493212 A CA 2493212A CA 2493212 A1 CA2493212 A1 CA 2493212A1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q30/00—Auxiliary means serving to assist or improve the scanning probe techniques or apparatus, e.g. display or data processing devices
- G01Q30/02—Non-SPM analysing devices, e.g. SEM [Scanning Electron Microscope], spectrometer or optical microscope
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01Q—SCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
- G01Q60/00—Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
- G01Q60/18—SNOM [Scanning Near-Field Optical Microscopy] or apparatus therefor, e.g. SNOM probes
- G01Q60/22—Probes, their manufacture, or their related instrumentation, e.g. holders
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/84—Manufacture, treatment, or detection of nanostructure
- Y10S977/849—Manufacture, treatment, or detection of nanostructure with scanning probe
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/84—Manufacture, treatment, or detection of nanostructure
- Y10S977/849—Manufacture, treatment, or detection of nanostructure with scanning probe
- Y10S977/86—Scanning probe structure
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S977/00—Nanotechnology
- Y10S977/84—Manufacture, treatment, or detection of nanostructure
- Y10S977/849—Manufacture, treatment, or detection of nanostructure with scanning probe
- Y10S977/86—Scanning probe structure
- Y10S977/863—Atomic force probe
Abstract
The invention relates to a combined method, according to which a high- resolution reproduction of a sample surface is registered using scanning for ce microscopy and a locally highly resolved chemical nature of the sample surface, said nature being correlated with the reproduction, is measured usi ng mass spectroscopy. The chemical analysis of the surface takes place after th e laser desorption of a limited surface area. To achieve said desorption, the surface is illuminated at each relevant point by pulses according to the optical near field principle. The optical near-field principle guarantees an analysis with a local resolution that provides unlimited diffraction. A holl ow tip of the measuring probe that is used permits the unique allocation of the chemical analysis to a selected surface area. The highly symmetrical arrangement enables a high degree of transmission of the generated molecular ions.
Description
JPK Instruments AG
Method for locally highly resolved, mass-spectroscopic characterization of surfaces using scanning probe technology The present invention relates to :~ method for high-resolution microscopic observation of the surface structure, and at the same time of the molecular composition associated with the observed structure elements, of a sample surface. The invention also relates to an apparatus having a specially adapted scanning force microscope and a specially adapted mass spectrometer for carrying out the method.
A scanning force microscope (SFM) sc<<ns the surface structure of a sample to be examined, by means of ~~ piezoelectric mechanism. The mechanism can be moved not only on the sample plane (x/y direction) but also at right angles to it in the z direction. First of all, the sample is moved into contact with ~~ tip by moving it in the z direction. The tip is located at the free end of a cantilever which is clamped in at one end. The cantilever typically has a length of between 10 um and 500 um, and the tip is ideally atomically sharp.
The cantilever and tip are generally integrated and, in most commercial products at the moment, are composed of silicon or silicon nitride. The bending of the cantilever as a result of the force between the sample and the tip is normally measured by means of the optical pointer principle, and is set to a desired (nominal) value.
In the so-called contact mode, an image of the sample surface is obtained as follows: while a section of the sample surface is being scanned, any further bending of the cantilever resulting from the sample topology is fed back to the nominal value. The setting of the scanning unit in the z direction as a function of each point on the x/y plane reflects the sample topology, and is recorded.
In the so-called intermittent contact mode, the cantilever is caused to oscillate close to its mechanical :=esonant frequency before being moved towards the sample. After being moved towards the sample, the tip then touches the sample briefly on one occasion in each oscillation cycle. This leads to attenuation of the oscillation and thus to a reduced oscillation amplitude, which is measured and is set to a specific value as a measure of the intensity of the interaction between the sample and the tip. The sample surface is now imaged as described above.
Time-of-flight (TOF) mass spectrosc~~py is used to examine the molecular composition of an analyte on the basis of the molecular masses of the components. The elemeni;s of a sample to be examined are changed from the solid phase to the gas phase in different ways in a vacuum system. By way of example, one sample region is bombarded with a laser pulse for this purpose. In the process, charged molecules or molecule fragments which are accelerated by means of electrodes in a flight tube: from which the air has been removed strike a detector after a flight path of, for example, 60 to 100 cm. The molecular weight is calculated from the time of flight:
the heavier the molecule, the longer is the time of flight. This method is highly sensitive and accurate; only subpeco molar quantities are required. In principle, it is technically possible to detect individual ions in a TOF arrangement. The error is around ~
0.05 Da per 1000 Da.
The primary aim of scanning force microscopy is to allow the state of the sample surface to be assessed. by imaging the structure. If the preconditions are ideal, the atomic structure of a sample surface can be resolved. This applies to surface of crystalline structures and, to a restricted extent, to high-order organic and inorganic adsorbates on surfaces. In this situations, the state of the sample surface can be assessed directly.
However, depending on the sample, tree resolution is generally not achieved, and the topography does not provide sufficient information to make an assessment of the state of a sample surface. In these situations, it is necessary to identi:Fy the local chemical nature or the local molecular composition of a sample surface by means other than microscopic structure analysis. 'this statement relates not only to scanning force microscopy but also to every other microscopic method (electron microscopy, optical microscopy, etc.). Methods are therefore used which combine microscopic imaging with chemical analysis, in the wide or narrow sense'. The following text describes two methods which are related to the method according to the method and are based on local ablation of the surface, followed by mass spectroscopy.
In laser disorption mass spectrometry (LAMMA), a laser pulse is focused onto a sample point chosen by means of conventional optical microscopy. This leads to local abla~:ion of the sample and to the production of molecule ions from the locally ablated material. The ions are accelerated in the electrical field and are identified on the basis of their molecular mass by means of a time of flight mass spectrometer. One arrangement from LAMMA (LAMMA 2000; Spengler B.
and Hubert, M.: Scanning Microprobe Matrix-Assisted Laser Desorption Ionization (SMALDI) Mass Spectrometry: Instrumentation for Sub-Micrometer Resolved LDI and MALDI Surface Analysis, J. Soc. Mass.
Spectrom. 13, 735-748, 2002) should he mentioned in particular, in which the described principle has been optimized for combined imaging of the structure by means of c~onfocal optical microscopy and local molecular composition by means of mass spectrometer of samples. In this arrangement, both the optical resolution and the minimum sample region from which ion: can be obtained and detected are diffraction-limited. An optical and analytical resolution of 0.5 um has been achieved in practice, that is to say the minimum analyzed sample region had a diameter of 0.5 um.
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is one analytical method for locally resolved chemical characteristic of material surfaces of an inorganic, organic and biological nature.
The method is based on time-resolve3 recording of secondary ions which are produced by bombardment of the surface with high-imaging primary ions (Cs+, Ga+). In this case, the primary ion beam is highly focused and is scanned over t:he sample. The secondary ions released during the process are accelerated into the flight tube of a TOF mass spectrometer. Since the effective verification depth is only about 1 nanometer, the measured mass spectrum is composed only of the chemical components from the uppermost molecular layers. The lateral resolution of the ion images is about 1 micrometer.
The methods as described above f~~r locally resolved chemical characterization of a sample surfa~~e vary with respect to the minimum analyzed sample region wit:~in the resolution range of conventional optical microscopy. Tlzis is inadequate for many requirements in medicine, engineering and science. By way of example, cell membranes are laterally organized in a complex manner.
In this case, so-called lipid rafts represent the functional units of a large number of membrane-bound processes. Their diameter is about 60 nanometers. Analysis of their individual composition will be of critical importance for complete understanding of the membrane-bound processes that have been mentioned.
The combination of structured imagin<~ in the nanometer range with mass spectroscopy with corresponding position resolution promises an answer to the requirements that have been mentioned, and to a large number of other requirements. A combination of a scanning probe technique (for example, SFM) with mass spectroscopy may be used for this purpose. In fact, so far, the option of combination of mass spectroscopy with high-resolution scanning force microscopy has been investigated in different ways by different authorities. Either sample material has been deliberatel;~ ablated by lateral injection of pulsed laser light into the gap between the sample and the SFM
tip, or pulsed laser light has been used to illuminate the sample, in the form of a pulse, through a glass fiber with a conical tip in a so-called aperture (SNOM (scanning near-field optical microscope).
Both strategies make use of the principle of near-field optics, that is to say the tip is used to produce an illumination spot which is considerably smaller than the smal:Lest possible diameter of an illumination spot produced by conventional optics.
This has made it possible to reproducibly produce holes with a diameter of a few nanometers. In both cases, ions that were produced were sucked out laterally from the tip region. However, surprisingly, it has not so far been possible to achieve an unambiguous association between ions and a defined region in the near field of the tip. This problem is a result of the ions being sucked out inefficiently from the near field of the tip and sample.
Our own experimental investigations and model calculations have confirmed the unsatisfactory finding: the transmission of ions that are produced into the flight tube of ~~ mass spectrometer is poor and is dependent in a manner which cannot be calculated on the geometric conditions immediately at the point at which the ions are produced.
In summary, universal chemical analysis of surfaces with a position resolution in the nanometer range has not yet been available.
The object of the invention is to specify an improved method and an improved apparatus in which ions are produced in a very small volume in the near field of a tip/sample region which can be selected by the scanning force microscope, and are passed on with a high transmission level for mass spectrometry.
According to the invention, the objeca is achieved by an apparatus as claimed in the independent claim 1, and by a method as claimed in the independent claim 7.
According to one aspect, a method is provided in which a scanning force microscope is operated with a cantilever with an integrated hollow tip. The hollow tip has a ~~mall aperture opening on the sample side. The aperture preferably has a diameter which is considerably smaller than the wavelength of the light that is used.
An illumination spot is thus produced on the sample on the basis of the principle of near-field optics, with a diameter which is considerably less than the diffraction-limited illumination spot of conventional optics. The hole in the ~~ip widens increasingly towards the rear side, where it has its large~a opening.
In particular, the method (i) allo~~s an unambiguous association between all the observed ions and ~~ defined sample region; (ii) association of the observed ions with the sample topology; and (iii) local resolution, both of the topology and of the local molecular composition, below the resolution uimit of conventional optical systems.
Scanning force microscopy is preferax~ly carried out conventionally, as described above, using the intermittent contact mode or the contact mode. The microscopy is pre:_erably carried out in a hard vacuum. As an alternative to scannin<~ force microscopy, it is also feasible to adapt other scanning probe techniques for use in the described method.
Method for locally highly resolved, mass-spectroscopic characterization of surfaces using scanning probe technology The present invention relates to :~ method for high-resolution microscopic observation of the surface structure, and at the same time of the molecular composition associated with the observed structure elements, of a sample surface. The invention also relates to an apparatus having a specially adapted scanning force microscope and a specially adapted mass spectrometer for carrying out the method.
A scanning force microscope (SFM) sc<<ns the surface structure of a sample to be examined, by means of ~~ piezoelectric mechanism. The mechanism can be moved not only on the sample plane (x/y direction) but also at right angles to it in the z direction. First of all, the sample is moved into contact with ~~ tip by moving it in the z direction. The tip is located at the free end of a cantilever which is clamped in at one end. The cantilever typically has a length of between 10 um and 500 um, and the tip is ideally atomically sharp.
The cantilever and tip are generally integrated and, in most commercial products at the moment, are composed of silicon or silicon nitride. The bending of the cantilever as a result of the force between the sample and the tip is normally measured by means of the optical pointer principle, and is set to a desired (nominal) value.
In the so-called contact mode, an image of the sample surface is obtained as follows: while a section of the sample surface is being scanned, any further bending of the cantilever resulting from the sample topology is fed back to the nominal value. The setting of the scanning unit in the z direction as a function of each point on the x/y plane reflects the sample topology, and is recorded.
In the so-called intermittent contact mode, the cantilever is caused to oscillate close to its mechanical :=esonant frequency before being moved towards the sample. After being moved towards the sample, the tip then touches the sample briefly on one occasion in each oscillation cycle. This leads to attenuation of the oscillation and thus to a reduced oscillation amplitude, which is measured and is set to a specific value as a measure of the intensity of the interaction between the sample and the tip. The sample surface is now imaged as described above.
Time-of-flight (TOF) mass spectrosc~~py is used to examine the molecular composition of an analyte on the basis of the molecular masses of the components. The elemeni;s of a sample to be examined are changed from the solid phase to the gas phase in different ways in a vacuum system. By way of example, one sample region is bombarded with a laser pulse for this purpose. In the process, charged molecules or molecule fragments which are accelerated by means of electrodes in a flight tube: from which the air has been removed strike a detector after a flight path of, for example, 60 to 100 cm. The molecular weight is calculated from the time of flight:
the heavier the molecule, the longer is the time of flight. This method is highly sensitive and accurate; only subpeco molar quantities are required. In principle, it is technically possible to detect individual ions in a TOF arrangement. The error is around ~
0.05 Da per 1000 Da.
The primary aim of scanning force microscopy is to allow the state of the sample surface to be assessed. by imaging the structure. If the preconditions are ideal, the atomic structure of a sample surface can be resolved. This applies to surface of crystalline structures and, to a restricted extent, to high-order organic and inorganic adsorbates on surfaces. In this situations, the state of the sample surface can be assessed directly.
However, depending on the sample, tree resolution is generally not achieved, and the topography does not provide sufficient information to make an assessment of the state of a sample surface. In these situations, it is necessary to identi:Fy the local chemical nature or the local molecular composition of a sample surface by means other than microscopic structure analysis. 'this statement relates not only to scanning force microscopy but also to every other microscopic method (electron microscopy, optical microscopy, etc.). Methods are therefore used which combine microscopic imaging with chemical analysis, in the wide or narrow sense'. The following text describes two methods which are related to the method according to the method and are based on local ablation of the surface, followed by mass spectroscopy.
In laser disorption mass spectrometry (LAMMA), a laser pulse is focused onto a sample point chosen by means of conventional optical microscopy. This leads to local abla~:ion of the sample and to the production of molecule ions from the locally ablated material. The ions are accelerated in the electrical field and are identified on the basis of their molecular mass by means of a time of flight mass spectrometer. One arrangement from LAMMA (LAMMA 2000; Spengler B.
and Hubert, M.: Scanning Microprobe Matrix-Assisted Laser Desorption Ionization (SMALDI) Mass Spectrometry: Instrumentation for Sub-Micrometer Resolved LDI and MALDI Surface Analysis, J. Soc. Mass.
Spectrom. 13, 735-748, 2002) should he mentioned in particular, in which the described principle has been optimized for combined imaging of the structure by means of c~onfocal optical microscopy and local molecular composition by means of mass spectrometer of samples. In this arrangement, both the optical resolution and the minimum sample region from which ion: can be obtained and detected are diffraction-limited. An optical and analytical resolution of 0.5 um has been achieved in practice, that is to say the minimum analyzed sample region had a diameter of 0.5 um.
Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is one analytical method for locally resolved chemical characteristic of material surfaces of an inorganic, organic and biological nature.
The method is based on time-resolve3 recording of secondary ions which are produced by bombardment of the surface with high-imaging primary ions (Cs+, Ga+). In this case, the primary ion beam is highly focused and is scanned over t:he sample. The secondary ions released during the process are accelerated into the flight tube of a TOF mass spectrometer. Since the effective verification depth is only about 1 nanometer, the measured mass spectrum is composed only of the chemical components from the uppermost molecular layers. The lateral resolution of the ion images is about 1 micrometer.
The methods as described above f~~r locally resolved chemical characterization of a sample surfa~~e vary with respect to the minimum analyzed sample region wit:~in the resolution range of conventional optical microscopy. Tlzis is inadequate for many requirements in medicine, engineering and science. By way of example, cell membranes are laterally organized in a complex manner.
In this case, so-called lipid rafts represent the functional units of a large number of membrane-bound processes. Their diameter is about 60 nanometers. Analysis of their individual composition will be of critical importance for complete understanding of the membrane-bound processes that have been mentioned.
The combination of structured imagin<~ in the nanometer range with mass spectroscopy with corresponding position resolution promises an answer to the requirements that have been mentioned, and to a large number of other requirements. A combination of a scanning probe technique (for example, SFM) with mass spectroscopy may be used for this purpose. In fact, so far, the option of combination of mass spectroscopy with high-resolution scanning force microscopy has been investigated in different ways by different authorities. Either sample material has been deliberatel;~ ablated by lateral injection of pulsed laser light into the gap between the sample and the SFM
tip, or pulsed laser light has been used to illuminate the sample, in the form of a pulse, through a glass fiber with a conical tip in a so-called aperture (SNOM (scanning near-field optical microscope).
Both strategies make use of the principle of near-field optics, that is to say the tip is used to produce an illumination spot which is considerably smaller than the smal:Lest possible diameter of an illumination spot produced by conventional optics.
This has made it possible to reproducibly produce holes with a diameter of a few nanometers. In both cases, ions that were produced were sucked out laterally from the tip region. However, surprisingly, it has not so far been possible to achieve an unambiguous association between ions and a defined region in the near field of the tip. This problem is a result of the ions being sucked out inefficiently from the near field of the tip and sample.
Our own experimental investigations and model calculations have confirmed the unsatisfactory finding: the transmission of ions that are produced into the flight tube of ~~ mass spectrometer is poor and is dependent in a manner which cannot be calculated on the geometric conditions immediately at the point at which the ions are produced.
In summary, universal chemical analysis of surfaces with a position resolution in the nanometer range has not yet been available.
The object of the invention is to specify an improved method and an improved apparatus in which ions are produced in a very small volume in the near field of a tip/sample region which can be selected by the scanning force microscope, and are passed on with a high transmission level for mass spectrometry.
According to the invention, the objeca is achieved by an apparatus as claimed in the independent claim 1, and by a method as claimed in the independent claim 7.
According to one aspect, a method is provided in which a scanning force microscope is operated with a cantilever with an integrated hollow tip. The hollow tip has a ~~mall aperture opening on the sample side. The aperture preferably has a diameter which is considerably smaller than the wavelength of the light that is used.
An illumination spot is thus produced on the sample on the basis of the principle of near-field optics, with a diameter which is considerably less than the diffraction-limited illumination spot of conventional optics. The hole in the ~~ip widens increasingly towards the rear side, where it has its large~a opening.
In particular, the method (i) allo~~s an unambiguous association between all the observed ions and ~~ defined sample region; (ii) association of the observed ions with the sample topology; and (iii) local resolution, both of the topology and of the local molecular composition, below the resolution uimit of conventional optical systems.
Scanning force microscopy is preferax~ly carried out conventionally, as described above, using the intermittent contact mode or the contact mode. The microscopy is pre:_erably carried out in a hard vacuum. As an alternative to scannin<~ force microscopy, it is also feasible to adapt other scanning probe techniques for use in the described method.
The locally resolved mass spectroscopy is carried out in parallel with or following the SFM imaging. In this case, the tip is in contact with the sample, or is in th.e immediate near field of the sample. For mass spectroscopy, a laser pulse is injected into the hollow tip from the rear side. Mater__al is ablated from the sample at each desired point on the sample b~~ means of a short laser pulse, and is passed on for mass spectro;~copy. For this purpose, the opening in the rear of the tip is actually connected to a flight tube, which is at a suitable electrical potential relative to the tip and to the sample, and is used fcr electrically sucking out the molecular ions which are produced after a laser pulse. The ions then preferably fly into a time of flight mass spectroscopy. Further advantages and expedient developments of the invention will become evident from the following description of exemplary embodiments and with reference to the drawing, in which:
Figure lA shows a schematic ilhzstration in order to explain a method based on one embodiment, showing a cross section through an arrangement with a scanning unit, a sample, a cantilever with a hollow tip, a flight tube and an objective;
Figure 1B shows an enlarged illustration of a section of an arrangement shown in :?figure lA;
Figure 2A shows a schematic illustration in order to explain a method based on a Further embodiment, showing a cross section through an arrangement with a scanning unit, a sample, a cantilever with a hollow tip, a flight tube and an objective; and Figure 2B shows an enlarged il:Lustration of a section of the arrangement shown in Figure 2A.
Figures lA, 1B, 2A and 2B show sche~r.atic illustrations in order to explain two embodiments of the methcd for locally high-resolution, mass-spectroscopic characterization of surfaces by means of a scanning probe technique. In both embodiments, scanning force micro-_ 7 _ scopy is combined with the capabili~~y to ablatesurface material from the sample at any pointx, y, and carry mass-spectroscopic out analysis of ionized sample materia:_. This done by using is a cantilever hole through 1 with it.
a tip 2 with an aa~ial, conical The hole opens with a definedaperture at the 3 of the tip.
apex The aperture is used as an outlet opening for a focused laser pulse onto the sample 30, and as an inlet: opening for molecular ions 20 which are produced after a laser pulse in the area of the 10 illuminated sample region.
The sample is generally illuminated coaxially with respect to the longitudinal axis of the tip, through the hole in it. The ions are preferably likewise extracted coaxial7.y with respect to the tip, and through the hole. For extraction, the flight tube 21 is connected to an electrical potential relative to the sample. An electrical field is formed, largely axially symmetrically with respect to the flight tube/tip axis. The field penetrates the hole in the tip and leads to extraction of the ions. If the flight tube is at a relatively low potential, ions with a positive total charge are extracted, and vice versa. The high degree of axial symme~:ry of the arrangement and thus of the field leads to largely axial extraction and to axial flight of the ions. Additional ion opti~:s in the flight tube (not illustrated) are used to pass back ions which do not fly exactly axially.
The area from which the material is ablated is governed by the size of the aperture in the hollow tip. The aperture diameter is typically considerably less than the wavelength of the light that is used.
The embodiments in Figures lA, 1B and 2A, 2B differ in how the laser light is injected: in the embodiment shown in Figures lA and 1B, an objective 11 is located at the side, alongside the flight tube, for focusing. The optical axis 12 is in:_tially at right angles to the axis of the flight tube 21. The light enters the flight tube via a window, is deflected in the axial direction by means of a mirror 13, and is focused in the hole in the tip. The mirror has a central hole 24 for the ions to pass through.
In the embodiment shown in Figures 2A and 2B, the objective is coaxial with respect to the flight tube. The flight tube is introduced into a central hole 24 in t:he objective. Collimated laser light is reflected into the beam path downstream from the objective.
In this case as well, the mirror has a central hole for the ions to pass through.
The features of the invention a;~ disclosed in the present description, in the claims and in the drawing may be significant to the implementation of the various embodiments of the invention both individually and in any given combination.
Figure lA shows a schematic ilhzstration in order to explain a method based on one embodiment, showing a cross section through an arrangement with a scanning unit, a sample, a cantilever with a hollow tip, a flight tube and an objective;
Figure 1B shows an enlarged illustration of a section of an arrangement shown in :?figure lA;
Figure 2A shows a schematic illustration in order to explain a method based on a Further embodiment, showing a cross section through an arrangement with a scanning unit, a sample, a cantilever with a hollow tip, a flight tube and an objective; and Figure 2B shows an enlarged il:Lustration of a section of the arrangement shown in Figure 2A.
Figures lA, 1B, 2A and 2B show sche~r.atic illustrations in order to explain two embodiments of the methcd for locally high-resolution, mass-spectroscopic characterization of surfaces by means of a scanning probe technique. In both embodiments, scanning force micro-_ 7 _ scopy is combined with the capabili~~y to ablatesurface material from the sample at any pointx, y, and carry mass-spectroscopic out analysis of ionized sample materia:_. This done by using is a cantilever hole through 1 with it.
a tip 2 with an aa~ial, conical The hole opens with a definedaperture at the 3 of the tip.
apex The aperture is used as an outlet opening for a focused laser pulse onto the sample 30, and as an inlet: opening for molecular ions 20 which are produced after a laser pulse in the area of the 10 illuminated sample region.
The sample is generally illuminated coaxially with respect to the longitudinal axis of the tip, through the hole in it. The ions are preferably likewise extracted coaxial7.y with respect to the tip, and through the hole. For extraction, the flight tube 21 is connected to an electrical potential relative to the sample. An electrical field is formed, largely axially symmetrically with respect to the flight tube/tip axis. The field penetrates the hole in the tip and leads to extraction of the ions. If the flight tube is at a relatively low potential, ions with a positive total charge are extracted, and vice versa. The high degree of axial symme~:ry of the arrangement and thus of the field leads to largely axial extraction and to axial flight of the ions. Additional ion opti~:s in the flight tube (not illustrated) are used to pass back ions which do not fly exactly axially.
The area from which the material is ablated is governed by the size of the aperture in the hollow tip. The aperture diameter is typically considerably less than the wavelength of the light that is used.
The embodiments in Figures lA, 1B and 2A, 2B differ in how the laser light is injected: in the embodiment shown in Figures lA and 1B, an objective 11 is located at the side, alongside the flight tube, for focusing. The optical axis 12 is in:_tially at right angles to the axis of the flight tube 21. The light enters the flight tube via a window, is deflected in the axial direction by means of a mirror 13, and is focused in the hole in the tip. The mirror has a central hole 24 for the ions to pass through.
In the embodiment shown in Figures 2A and 2B, the objective is coaxial with respect to the flight tube. The flight tube is introduced into a central hole 24 in t:he objective. Collimated laser light is reflected into the beam path downstream from the objective.
In this case as well, the mirror has a central hole for the ions to pass through.
The features of the invention a;~ disclosed in the present description, in the claims and in the drawing may be significant to the implementation of the various embodiments of the invention both individually and in any given combination.
Claims (11)
1. An apparatus for a scanning microscope, in particular a scanning force microscope, comprising a measurement probe which defines a near field, and having a scanning unit which allows the measurement probe to move relative to a sample in all three spatial directions, in conjunction with a mass spectrometer with an ionization unit, an extraction unit and an analysis unit, characterized in that the measurement probe has a hollow tip so that the near field of the measurement probe can be used by the ionization unit in such a way that ions are formed only in the near field of the measurement probe, and the shape of the measurement probe allows an essentially axially symmetrical field distribution of the extraction unit with respect to the axis of the analysis unit.
2. The apparatus as claimed in claim 1, characterized in that the measurement probe is a cantilever.
3. The apparatus as claimed in claim 1 or 2, characterized in that the sample can be moved in all three spatial directions by means of the scanning unit.
4. The apparatus as claimed in one of the preceding claims, characterized in that the ionization unit has a laser, light beams which are indicated by the laser are focused off-axis and are then deflected by means of a mirror in an axial direction, with the mirror having an axial hole which allows the ions to pass through to the analysis unit.
5. The apparatus as claimed in one of claims 1 to 3, characterized in that the ionization unit has a laser, and light beams which are indicated by the laser are deflected by means of a mirror in an axial direction and are then focused by means of a focusing device, with the mirror and the focusing device each having an axial hole which allows the ions to pass through to the analysis unit.
6. The apparatus as claimed in one of claims 1 to 3, characterized in that the ionization unit has a laser, and light beams which are indicated by the laser are passed to the measurement probe and cause ionization in the near field of the measurement probe by means of field amplification.
7. A method for high-resolution examination of a measurement sample using a combined scanning probe microscope, in particular a scanning force microscope, wherein the scanning probe microscope is first of all used to record an image of the measurement sample, in particular of the topography of the measurement sample, and wherein a mass spectrometer is then used for destructive, chemical characterization of at least subareas of sections of the measurement sample which are covered by the image.
8. The method as claimed in claim 7, characterized in that the selected areas are chosen successively such that the entire area imaged by the scanning probe microscope is analyzed, thus additionally resulting in a chemical image of the sample.
9. The method as claimed in one of claims 7 or 8, characterized in that further ablation of the measurement sample leads to high-resolution depth information.
10. The method as claimed in one of claims 7 to 9, characterized in that the distance between two points for ionization can be chosen by analysis of the area ablated by an ionization process, such that this leads to uniform ablation or the measurement sample.
11. The method as claimed in one of claims 7 to 10, characterized in that the information from scanning probe microscopy and from mass spectrometry can be compared with high lateral resolution.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10234507 | 2002-07-24 | ||
| DE10234507.4 | 2002-07-24 | ||
| PCT/DE2003/002493 WO2004017019A1 (en) | 2002-07-24 | 2003-07-24 | Method for locally highly resolved, mass-spectroscopic characterisation of surfaces using scanning probe technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2493212A1 true CA2493212A1 (en) | 2004-02-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002493212A Abandoned CA2493212A1 (en) | 2002-07-24 | 2003-07-24 | Method for locally highly resolved, mass-spectroscopic characterization of surfaces using scanning probe technology |
Country Status (9)
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| US (1) | US7442922B2 (en) |
| EP (1) | EP1523652B1 (en) |
| JP (1) | JP2005534041A (en) |
| CN (1) | CN1311221C (en) |
| AT (1) | ATE427475T1 (en) |
| AU (1) | AU2003260246A1 (en) |
| CA (1) | CA2493212A1 (en) |
| DE (2) | DE50311375D1 (en) |
| WO (1) | WO2004017019A1 (en) |
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| JP2006125984A (en) * | 2004-10-28 | 2006-05-18 | Japan Science & Technology Agency | Measuring instrument having daisy shaped cantilever |
| WO2006081240A1 (en) * | 2005-01-27 | 2006-08-03 | The George Washington University | Protein microscope |
| DE102006056929B4 (en) * | 2006-12-04 | 2010-09-02 | Bruker Daltonik Gmbh | Mass spectrometry with laser ablation |
| WO2009032904A1 (en) * | 2007-09-05 | 2009-03-12 | Government Of The United States Of America, Represented By The Secretary, Department Of Health And Human Services | Probe and method for obtaining three-dimensional compositional maps of a biological sample |
| US7924423B2 (en) * | 2008-08-11 | 2011-04-12 | Ut-Battelle, Llc | Reverse photoacoustic standoff spectroscopy |
| US7961313B2 (en) * | 2008-08-11 | 2011-06-14 | Ut-Battelle, Llc | Photoacoustic point spectroscopy |
| US8194246B2 (en) * | 2008-08-11 | 2012-06-05 | UT-Battellle, LLC | Photoacoustic microcantilevers |
| US8448261B2 (en) * | 2010-03-17 | 2013-05-21 | University Of Tennessee Research Foundation | Mode synthesizing atomic force microscopy and mode-synthesizing sensing |
| US20110231966A1 (en) * | 2010-03-17 | 2011-09-22 | Ali Passian | Scanning probe microscopy with spectroscopic molecular recognition |
| US8080796B1 (en) | 2010-06-30 | 2011-12-20 | Ut-Battelle, Llc | Standoff spectroscopy using a conditioned target |
| US8519330B2 (en) * | 2010-10-01 | 2013-08-27 | Ut-Battelle, Llc | Systems and methods for laser assisted sample transfer to solution for chemical analysis |
| CN102183679B (en) * | 2011-03-16 | 2012-12-19 | 中国科学院合肥物质科学研究院 | In-situ quasi synchronous detection method for detecting physicochemical properties of micro and nano structures |
| CN102339721B (en) * | 2011-09-28 | 2014-03-12 | 厦门大学 | Near-field needle-point reinforced photoionization ion source |
| US9269557B2 (en) * | 2012-09-07 | 2016-02-23 | Canon Kabushiki Kaisha | Ionization device, mass spectrometer including the ionization device, and image generation system including the ionization device |
| CN103207035B (en) * | 2013-05-14 | 2015-07-15 | 南京因艾生生物科技有限公司 | Force spectrometer for measuring intermolecular forces |
| EP2824445B1 (en) * | 2013-07-08 | 2016-03-02 | Fei Company | Charged-particle microscopy combined with raman spectroscopy |
| CN104697982B (en) * | 2015-03-17 | 2017-07-07 | 北京理工大学 | High-space resolution laser differential confocal mass spectrum micro imaging method and device |
| CN106338546A (en) * | 2016-08-18 | 2017-01-18 | 东南大学 | High-spatial-resolution imaging mass spectrometry device |
| JP7031626B2 (en) * | 2019-03-13 | 2022-03-08 | オムロン株式会社 | The sensor head |
| CN112816739A (en) * | 2019-11-18 | 2021-05-18 | 中国科学院大连化学物理研究所 | Scanning chemical reaction microscopic imaging method and application |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5467642A (en) * | 1992-11-06 | 1995-11-21 | Hitachi, Ltd. | Scanning probe microscope and method of control error correction |
| US5278406A (en) * | 1992-11-12 | 1994-01-11 | Hamamatsu Photonics K.K. | Apparatus for detecting information contained in electrons emitted from sample surface |
| JP3270165B2 (en) * | 1993-01-22 | 2002-04-02 | セイコーインスツルメンツ株式会社 | Surface analysis and processing equipment |
| US5444260A (en) * | 1993-07-01 | 1995-08-22 | Midwest Reasearch Institute | Atomic-level imaging, processing and characterization of semiconductor surfaces |
| US5440124A (en) * | 1994-07-08 | 1995-08-08 | Wisconsin Alumni Research Foundation | High mass resolution local-electrode atom probe |
| JPH0894646A (en) * | 1994-09-22 | 1996-04-12 | Shimadzu Corp | Surface analyzer |
| US6080586A (en) * | 1996-04-05 | 2000-06-27 | California Institute Of Technology | Sub-micron chemical imaging with near-field laser desorption |
| US6405137B1 (en) * | 1996-12-31 | 2002-06-11 | Ta Instruments, Inc. | Method and apparatus for performing chemical analysis using imaging by scanning thermal microscopy |
| GB9719697D0 (en) * | 1997-09-16 | 1997-11-19 | Isis Innovation | Atom probe |
| US6466309B1 (en) * | 1999-02-26 | 2002-10-15 | California Institute Of Technology | Method and apparatus for chemical and topographical microanalysis |
| JP2000283909A (en) * | 1999-03-30 | 2000-10-13 | Jeol Ltd | Surface observation device |
| US6897015B2 (en) * | 2000-03-07 | 2005-05-24 | Bioforce Nanosciences, Inc. | Device and method of use for detection and characterization of pathogens and biological materials |
| US6875981B2 (en) * | 2001-03-26 | 2005-04-05 | Kanazawa Institute Of Technology | Scanning atom probe and analysis method utilizing scanning atom probe |
| WO2003008941A2 (en) * | 2001-07-17 | 2003-01-30 | Bioforce Nanosciences, Inc. | Combined molecular blinding detection through force microscopy and mass spectrometry |
| JP3902925B2 (en) * | 2001-07-31 | 2007-04-11 | エスアイアイ・ナノテクノロジー株式会社 | Scanning atom probe |
| US6566653B1 (en) * | 2002-01-23 | 2003-05-20 | International Business Machines Corporation | Investigation device and method |
| US8093144B2 (en) * | 2002-05-24 | 2012-01-10 | Massachusetts Institute Of Technology | Patterning of nanostructures |
| US6941033B2 (en) * | 2002-06-25 | 2005-09-06 | National Research Council Of Canada | Method and device for manipulating microscopic quantities of material |
-
2003
- 2003-07-24 DE DE50311375T patent/DE50311375D1/en not_active Expired - Fee Related
- 2003-07-24 AT AT03787732T patent/ATE427475T1/en not_active IP Right Cessation
- 2003-07-24 DE DE10393504T patent/DE10393504D2/en not_active Expired - Fee Related
- 2003-07-24 JP JP2004528433A patent/JP2005534041A/en active Pending
- 2003-07-24 AU AU2003260246A patent/AU2003260246A1/en not_active Abandoned
- 2003-07-24 US US10/521,563 patent/US7442922B2/en not_active Expired - Fee Related
- 2003-07-24 CA CA002493212A patent/CA2493212A1/en not_active Abandoned
- 2003-07-24 WO PCT/DE2003/002493 patent/WO2004017019A1/en active Application Filing
- 2003-07-24 CN CNB038227355A patent/CN1311221C/en not_active Expired - Fee Related
- 2003-07-24 EP EP03787732A patent/EP1523652B1/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP1523652B1 (en) | 2009-04-01 |
| DE50311375D1 (en) | 2009-05-14 |
| CN1311221C (en) | 2007-04-18 |
| EP1523652A1 (en) | 2005-04-20 |
| WO2004017019A1 (en) | 2004-02-26 |
| DE10393504D2 (en) | 2005-06-23 |
| ATE427475T1 (en) | 2009-04-15 |
| US20060097164A1 (en) | 2006-05-11 |
| CN1685195A (en) | 2005-10-19 |
| US7442922B2 (en) | 2008-10-28 |
| AU2003260246A1 (en) | 2004-03-03 |
| JP2005534041A (en) | 2005-11-10 |
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| EEER | Examination request | ||
| FZDE | Discontinued |