Scanning probe microscopy using sensor molecules for improving light transmission to samples

Abstract

A scanning probe microscope and microscope operating method utilizes at least one material having a dielectric constant (ε) and a resonant sensor material between a metal probe tip and a sample surface. When electromagnetic radiation from a light source is transmitted to the junction between the metal probe tip and the sample, absorption of the electromagnetic radiation by the resonant sensor material, which depends on the dielectric constant of the at least one material of the sample, is detected.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application may enjoy the benefit of priority of U.S. Provisional Patent Application No. 62 / 676,878, filed on May 25, 2018, and is incorporated into this specification by reference. Background Art

[0003] Photo-induced force microscopy (PiFM) utilizes a metal-coated atomic force microscopy (AFM) probe tip to detect the optically induced force and / or force gradient acting between the AFM probe tip and the sample, measuring the local optical polarization of the sample beneath the tip tip. Key factors determining signal strength are the metal coating, the tip shape, and the field enhancement caused by the P-polarization of the excitation light (an electric field nearly parallel to the tip axis). The field enhancement is strongest at the tip tip and decays rapidly with increasing distance from the tip tip (~10s nm). While metals typically have a flat response as a function of wavelength to infrared (IR) excitation sources, samples may exhibit at least one pronounced response corresponding to an oscillatory resonance related to the sample's chemical makeup. More frequently, the tip tip and sample may also exhibit exotic resonances, such as plasmon resonances. PiFM records strong signals at wavelengths associated with resonance. Because the oscillating resonance wavelength is associated with a specific molecular composition, PiFM spectra can reveal the local chemical composition of a sample with nm-scale spatial resolution.

[0004] Other types of nanoscale instruments that rely on oscillations and plasmon resonances to investigate the chemical structure of a sample include photothermal induced resonance (PTIR), where absorption of excitation light induces thermal expansion of the sample, thereby changing the deflection signal of the AFM cantilever, and scattering scanning near-field optical microscopy (s-SNOM), in which near-field photons scattered from the probe tip are collected by a remote photodetector. All of these techniques (PiFM, PTIR, and s-SNOM) detect the resonance of the sample. Consequently, they are largely useless for samples that are not IR-active, meaning that IR excitation does not induce oscillation resonances. There are many important samples that are either IR-inactive or cannot be oscillated resonantly by the currently used IR laser sources. In particular, quantum cascade lasers that generate tunable IR light continuously with sufficient power typically operate in the range of approximately 5 to 13 microns. Some specific examples of materials that are not IR active in this spectral range include dielectrics such as two-dimensional materials, silicon, various metals, and silicon germanium (SiGe). Many of these materials are already actively used in various fields, and it is advantageous to be able to highlight them with nanometer-scale spatial resolution. Summary of the Invention

[0005] A scanning probe microscope and microscope operating method utilizes a resonant material having at least one material having a dielectric constant ε between a metal probe tip and a sample surface. When electromagnetic radiation from a light source is transmitted to the junction between the metal probe tip and the sample, the electromagnetic radiation is detected by the resonant sensor material, which absorbs the electromagnetic radiation, depending on the dielectric constant of the at least one material of the sample.

[0006] A scanning probe microscope according to an embodiment of the present invention includes: a cantilever having a metal probe tip for connecting at least one material having a dielectric constant ε and a sample; a light source for transmitting electromagnetic radiation to the connection between the metal probe tip and the sample; an oscillation drive device connected to the cantilever and oscillating the cantilever; a resonant sensor material located between the metal probe tip and the sample surface; and a detection system for detecting electromagnetic radiation absorption by the resonant sensor material, wherein the electromagnetic radiation absorption by the resonant sensor material depends on the dielectric constant ε of the at least one material of the sample.

[0007] According to one embodiment of the present invention, a scanning probe microscope operation method includes the following steps: driving a cantilever with a metal probe tip of the scanning probe microscope, thereby oscillating the metal probe tip and the sample to connect at least one material having a dielectric constant ε; as a step of modulating a light source that irradiates the connection between the probe tip and the sample with electromagnetic radiation, a resonant sensor material modulates the light source located between the metal probe tip and the sample surface; and as a step of detecting absorption of electromagnetic radiation by the resonant sensor material, the absorption of electromagnetic radiation by the resonant sensor material depends on the dielectric constant ε of at least one material of the sample to detect the absorption of the electromagnetic radiation.

[0008] Further aspects and advantages of the present invention will become apparent from the accompanying drawings and the following detailed description, illustrating by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a block diagram of a scanning probe microscope according to an embodiment of the present invention.

[0010] Figure 2A Cross-sectional view of a sample showing SiGe lines repeated in an array of SiO2.

[0011] Figure 2B Examples are in Figure 2A AFM morphology of SiGe lines is shown in the sample.

[0012] Figure 2C Example of measurement with metal-coated probe tip Figure 2A A sample of PiFM.

[0013] Figure 2D Example Figure 2A The SiGe line of the sample is included in the acquired PiFM spectrum.

[0014] Figure 2E According to an embodiment of the present invention, the tip is located Figure 2A The sample SiGe line is used with a display of 1100cm -1 The vibrations of Si-O molecules around the tip of a metal probe are measured using a thin coating of sensor material. Figure 2A A sample of PiFM.

[0015] Figure 2F According to an embodiment of the present invention, the tip is located Figure 2A The sample SiGe line is used with a display of 1266cm -1 The PiFM spectrum obtained with a thin coating of sensor molecular material on the metal probe tip shows a PiF signal of considerable magnitude.

[0016] Figure 2GAccording to an embodiment of the present invention, an example of using a SiGe -1 There are no IR active vibration modes in the -1 The PiFM image clearly highlights the thin coating of sensor material on the SiGe wire measured by the metal probe tip. Figure 2A A sample of PiFM.

[0017] Figure 3 Schematic showing the mutually different electric fields when the probe tip is positioned on materials with different dielectric constants.

[0018] Figure 4 1 shows the IR spectrum and PiFM spectrum of the reporting sensor material when the probe tip is positioned on materials with various dielectric constants according to an embodiment of the present invention.

[0019] Figure 5A This is an image showing silver nanowires embedded in a polymer generated by topography, according to an embodiment of the present invention.

[0020] Figure 5B An image of silver nanoparticles embedded in a polymer produced by PiFM is shown according to an embodiment of the present invention.

[0021] Figure 6 is a flowchart of a scanning probe microscope operation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] As mentioned above, one of the media parameters that controls the intensity of the PiFM signal is the enhancement of the local electric field beneath the apex of a metal atomic force microscope (AFM) probe tip. The magnitude of the electric field depends on the degree of electrical bonding between the metal probe tip and the sample / substrate structure. For example, as is well known for all near-field imaging tools (PTIR, s-SNOM, and PiFM), the response of thin samples is enhanced if the sample is deposited on a metal substrate. This is because the gap electric field (between the probe tip and the sample surface) is enhanced due to the metal's very high dielectric constant, and the effective electric field is higher for samples than for non-metallic substrates. The degree of gap field enhancement depends on the dielectric constant of the substrate; higher dielectric constants result in stronger field enhancement. Thus, if a thin, uniform material A with a unique oscillation resonance in f1 is present on two materials (B and C) with different dielectric constants (εB > εC), the PiFM signal in f1 will be stronger when it is located on B. This effect is the same even if the two materials B and C are not IR-active. Thus, materials B and C can be distinguished by a uniform film coating with an oscillatory resonance accessible by a laser source. While materials with different dielectric constants can be distinguished, chemical identification will not be as clear as obtaining a full PiFM spectrum. Even so, the ability to highlight different materials based on their different dielectric constants is a useful feature when normal IR interrogation does not provide much information. Material A can be used to infer information about the actual sample composed of materials B and C and can therefore be considered a sensor molecule material. Rather than coating the sample surface with a uniform layer of sensor molecules, the probe tip can be used instead to coat it with sensor molecules, leaving the sample surface exposed for B and C. When imaging the sample with a tip coated with sensor molecule material A, the effect will be the same, i.e., the PiFM signal will show a stronger response at f1 when the higher dielectric constant tip is positioned over sample B.

[0023] Figure 1 An embodiment of a scanning probe microscope 100 is shown in which a metal AFM probe tip 102 is coated with a layer of sensor material 104. The scanning probe microscope 100 operates as a phototransistor force microscope (PiFM), in which one mechanical resonance of a cantilever 106 is used to track topography, while another mechanical resonance is used to measure phototransistor forces or force gradients. The cantilever 106 is vibrated at a frequency fj by an oscillating drive 108, such as a pressure point transducer, with the metal probe tip 102. A light source 110, such as a tunable laser 110, is modulated or pulsed at a frequency fm, where fm=fi+fj or fm=fj-fi, where fi and fj are the i-th and j-th mechanical resonances of the cantilever 106. Figure 1 A combination of fj=j1 and fi=fo is shown.

[0024] The nonlinear interaction between the dither motion and the optically guided force results in a mixed frequency of cantilever oscillation at fj. The choice of frequencies fj and fj can be based on the bandwidth of the detection system 112. However, one approach is to use fj as the first flexural mode and fj as the second flexural mode of the cantilever. In this setting, the Van der Waals interaction is measured to measure the topography in the second flexural mode, while the sidebands generated from the optically guided force mixed with the Van der Waals interaction are measured in the first resonant mode of the cantilever.

[0025] like Figure 1 As shown, electromagnetic radiation from a tunable laser 110 is directed toward an interface between a metal probe tip 102 and a sample 114. Sample 114 comprises at least one material having a dielectric constant ε and at least one other material having a different dielectric constant using one or more optical elements 116. One or more optical elements 116 may include a parabolic mirror for focusing the electromagnetic radiation at the interface. Metal probe tip 102 may be a solid metal tip or a metal-coated tip. Sample 114 is disposed on a substrate 118 of an XYZ sample scanner capable of moving the sample in the X, Y, and Z directions.

[0026] The detection system 112 includes an AFM feedback light source 122 (e.g., a laser), a light detector 124, and a PiFM controller 126, as known components. The AFM feedback light source 122 and the light detector 124 operate to optically detect the optically guided force and / or force gradient acting between the probe tip 102 and the sample 114, and the oscillation of the cantilever 106 due to the Van der Waals interaction. The PiFM controller 126 includes electronics for processing signals generated by the light detector 124 in response to light received from the AFM feedback light source reflected from the cantilever 106. The PiFM controller 126 can detect the absorption of electromagnetic radiation from the light source 110 by the resonant sensor material 104, which depends on the dielectric constant of the material within the sample. In one embodiment, the PiFM controller 126 measures the optically guided force or force gradient acting on the probe tip 102 when connected to the sample 104, and can thereby detect the absorption of electromagnetic radiation by the resonant sensor material 104. In one embodiment, the PiFM controller 126 also detects electromagnetic radiation scattered by the combination of the probe tip, the resonant sensor material, and the sample in the connection between the probe tip and the sample, and can thereby detect absorption of electromagnetic radiation by the resonant sensor material 104. A detailed description of the scanning probe microscope 100 is described in U.S. Patent No. 8,739,311 B2, which is incorporated herein by reference.

[0027] PiFM can be used to measure the optical conductivity generated by the absorption of excitation light by a sample when the excitation wavelength can excite an oscillation or other resonance in the sample. However, if the excitation wavelength cannot excite a specific oscillation resonance in the sample due to the lack of a source of the right wavelength or the fact that the oscillation mode is "not IR active", PiFM will not be able to detect all signals at that wavelength. For example, in the case of samples composed of SiO2 and SiGe, standard PiFM uses a wavelength of ~1100 cm -1 The absorption under the IR spectrum allows the identification of SiO2 moieties, whereas SiGe has no IR-active oscillation modes within the range of conventional laser sources used with PiFM and is therefore undetectable.

[0028] Figure 2A Cross-sectional view of a sample of SiGe lines repeated in an array of SiO2. Figure 2A As shown in Figure 1, the adjacent SiGe lines are spaced 209nm apart and the width of each SiGe line is 24nm. Since the SiGe line is slightly longer than the SiO2 array, Figure 2B The AFM topography shown clearly shows the SiGe lines. When measuring such a sample with a metal-coated probe tip in PiFM, Figure 2C Shown at 1120cm -1 The SiO2 array is clearly visible, and the SiGe lines appear as dark lines. Unfortunately, there is no quantum cascade laser (QCL) wavelength available for detecting SiGe lines. Figure 2D As shown, when the PiFM spectrum including the SiGe line is obtained, it can be seen that there is a 1100cm -1 However, when using a signal with 1266cm -1 When the metal probe tip is thinly coated with a sensor molecular material having an IR active oscillation peak, if Figure 2E and 2F The PiFM spectrum shown is located at the tip of the SiGe line, and is attached to 1100 cm -1 The Si-O vibration around 1266 cm -1 The PiF signal is shown to be of considerable size. Figure 2G As shown in the example, the PiFM image shows that even if SiGe is at 1270 cm -1 The absence of IR-active vibrational modes also clearly highlights the SiGe lines. This additional coating is called a sensor material because of its ability to map invisible materials to IR excitation.

[0029] This result is generated by different electric fields enhanced in the probe tip, depending on the sample's dielectric constant. The higher the dielectric constant, the stronger the field enhancement seen by the sensor's molecular material. Consequently, the excitation light intensity is more effectively enhanced when the probe tip is positioned over a material with a higher dielectric constant than when the probe tip is positioned over a material with a lower dielectric constant.

[0030] Figure 3 This diagram schematically illustrates the differing electric fields when the probe tip is positioned on materials with different dielectric constants. When the probe tip is positioned on platinum (Pt), the maximum field enhancement is M = 232. However, when the probe tip is positioned above SiO2, the maximum field enhancement is M = 68. Thus, the sensor molecule reacts more strongly in its own IR-active vibrational mode when positioned on a material with a higher dielectric constant. This demonstrates the material-dependent contrast that PiFM can generate when the sample contains constituent elements that are not IR-active. Figure 4 Reports the IR and PiFM spectra of the sensor material when the probe tip is positioned on materials with various dielectric constants.

[0031] Since light is quite transparent to non-metallic materials, the presence of metal embedded within a non-metal can affect the field enhancement. Thus, using the vibrational modes of the sensor molecules, the embedded structure can also be imaged. Figure 5A and Figure 5B is an image showing that silver nanowires embedded in a polymer are effectively imaged in one of the oscillation modes of the sensor material. Figure 5A An image generated by topography is shown. Figure 5B Shown are images generated by PiFM.

[0032] AFM probe tips containing sensor materials can be prepared using various methods. One similar approach involves placing the probe tip in an environment where the sensor material is present as a vapor, coating the tip via condensation from the vapor. A practical example of this is placing the probe tip in a small enclosure containing the polymeric elastomer material PDMS (polydimethylsiloxane). Typically, after several days of exposure to this environment, a nanoscopic layer of the siloxane-containing material forms on the probe tip, allowing it to function as the sensor material. A variation of this technique involves placing the probe tip in an evaporator (a vacuum enclosure that heats a vial of sensor material to evaporate it), where the evaporated material is vacuum-deposited onto the tip. Another similar approach involves placing the probe tip in a liquid containing a suitable species for self-assembly of a monolayer of the desired sensor material, thereby generating a self-assembled monolayer of the material on the tip. Methods for generating self-assembled organic layers have been widely reported in the scientific literature. Another similar way to create a thin layer of sensor material is by dip coating, where the probe tip is immersed in a solution containing a specific concentration of sensor material in a solvent. If the tip is removed from the solution, the solvent evaporates, leaving behind a coating of sensor material.

[0033] In one embodiment, the sensor material 104 used in the metal probe tip 102 has an absorption resonance within the wavelength range of the tunable laser light 110. The absorption resonance of the sensor material 104 can be within the infrared or visible wavelength range. In one embodiment, the sensor material 104 can be a thin film of a self-assembled material, a monolayer of material attached to at least the apex of the metal probe tip 102. In some embodiments, the sensor material 104 can be particles in the form of molecular clusters parallel to the axis of the tip and having a thickness of no more than 50 nm. As used herein, "particles" refers to small amounts of material ranging from simple single molecules to particles visible to the naked eye (fractions of a mm). Furthermore, as used herein, "parallel to the axis of the tip" refers to a perpendicular direction along the length of the tip, i.e., a direction perpendicular to the surface of the XYZ sample scanner 120 facing the probe tip. Additionally, as used herein, "near the apex of the tip" refers to the range within which the PiFM force is generated between the tip and the sample, which is typically a maximum of a few nm and a maximum of 100 nm. As described above, the sensor material 104 used on the metal probe tip 102 can be at least one silicone-containing material having an absorption resonance that can be generated by electromagnetic radiation generated by the tunable laser 110.

[0034] Reference Figure 6A flow chart illustrating a method for operating a scanning probe microscope, such as scanning probe microscope 100, according to an embodiment of the present invention is provided. At block 602, a cantilever having a metal probe tip of the scanning probe microscope is driven into oscillation, whereby the metal probe tip connects at least one material having a dielectric constant ε to a sample. At block 604, a light source is modulated to illuminate the connection between the probe tip and the sample with electromagnetic radiation, wherein a resonant sensor material is located between the metal probe tip and the sample surface. At block 606, absorption of the electromagnetic radiation by the resonant sensor material is detected, where the absorption of the electromagnetic radiation by the resonant sensor material is dependent on the dielectric constant ε of the at least one material of the sample.

[0035] In general, the components of the embodiments described in this specification and illustrated in the figures are readily understood to be configurable and designed into a wide variety of different configurations. Accordingly, the detailed descriptions of various embodiments, as illustrated in the figures, are not intended to limit the scope of the present disclosure but are merely representative of various embodiments. Although various aspects of the embodiments are illustrated in the drawings, unless otherwise indicated, the drawings are not drawn to scale.

[0036] The present invention may be embodied in other forms without departing from the spirit or essential characteristics thereof. The described embodiments should be considered in all respects as non-restrictive and illustrative. Therefore, the scope of the present invention should be reflected in the scope of the claims rather than in this detailed description. All modifications within the meaning and scope of the claims are intended to be included within their scope.

[0037] References to features, advantages, or similar expressions throughout this specification do not imply that all features and advantages achievable with the present invention are included in or within any single embodiment of the present invention. Rather, references to features and advantages are to be understood as meaning that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, throughout this specification, discussions of features and advantages, and similar expressions, may refer to the same embodiments, but are not necessarily limited thereto.

[0038] Furthermore, the features, advantages, and characteristics described herein may be combined in any suitable manner in more than one embodiment. Those skilled in the relevant art will recognize, based on the teachings herein, that the present invention may be practiced without one or more of the features or advantages of a particular embodiment. In another example, additional features and advantages may be recognized in a particular embodiment that are not present in all embodiments of the invention.

[0039] Throughout this specification, references to "one embodiment," "an embodiment," or similar expressions refer to at least one embodiment of the present invention encompassing a particular feature, structure, or characteristic described in connection with the embodiment indicated. Thus, throughout this specification, "one embodiment," "an embodiment," and similar expressions may all refer to the same embodiment, but this is not necessarily the case.

[0040] In the above description, specific details of various embodiments are provided. However, some embodiments may be implemented without such specific details. In another example, for the sake of brevity and clarity of description, a specific method, step, component, structure, and / or function may not be described in greater detail than in the various embodiments that may implement the present invention.

[0041] The actions of the methods of this specification are shown and described in a specific order, but the order of the actions of each method can be reversed to perform specific actions, or can be changed so that at least a portion of a specific action can be performed simultaneously with another action. In another embodiment, the instructions or subordinate actions of individual actions can be performed intermittently and / or alternately.

[0042] Furthermore, it should be noted that at least a portion of the actions of the methods described herein may be implemented using software stored on a computer-readable storage medium for execution by a computer. As an example, an embodiment of a computer program product includes a computer-readable storage medium storing a computer-readable program.

[0043] Computer-usable or computer-readable storage media can be electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems (or devices or apparatus). Examples of non-transitory computer-usable and computer-readable storage media include semiconductor or solid-state memory, magnetic tape, removable computer disks, RAM (random access memory), ROM (read-only memory), rigid magnetic disks, and optical disks. Current examples of optical disks include CD-ROMs (compact disks with read only memory), CD-R / Ws (compact disks with read / write), and digital versatile disks (DVDs).

[0044] As another solution, the embodiments of the present invention can be implemented entirely by hardware or a solution comprising all hardware and software elements. In embodiments using software, the software may include firmware, resident software, microcode, etc., but is not limited thereto.

[0045] While particular embodiments of the present invention have been described and illustrated, the present invention is not limited to the particular forms or arrangements of parts so described and illustrated. The scope of the present invention should be defined by the scope of the claims and their equivalents.

Claims

1. A scanning probe microscope, comprising: a cantilever having a metal probe tip for connecting at least one material having a dielectric constant (ε) and a sample; a light source for transmitting electromagnetic radiation to the junction between the metal probe tip and the sample; an oscillation driving device connected to the cantilever and oscillating the cantilever; a resonant sensor material located between the metal probe tip and the sample surface, the resonant sensor material being attached to the probe tip; a detection system as a detection system for detecting the absorption of electromagnetic radiation by a resonant sensor material, the absorption of electromagnetic radiation by said resonant sensor material being dependent on the dielectric constant (ε) of at least one material of said sample, The resonant sensor material has an absorption resonance within the wavelength range of the light source.

2. The scanning probe microscope according to claim 1, wherein The detection system measures the light-transmitting force or force gradient acting on the probe tip when connected to the sample, thereby detecting the absorption of electromagnetic radiation by the resonant sensor material.

3. The scanning probe microscope according to claim 1, wherein The detection system detects the electromagnetic radiation scattered by the combination of the probe tip, the resonant sensor material, and the sample in the connection between the probe tip and the sample, and further detects the electromagnetic radiation absorbed by the resonant sensor material.

4. The scanning probe microscope according to claim 1, wherein The light source includes a tunable laser, and the resonant sensor material has an absorption resonance within the wavelength range of the tunable laser.

5. The scanning probe microscope according to claim 1, wherein The resonant sensor material comprises a thin film of material attached to at least the apex of the probe tip.

6. The scanning probe microscope according to claim 1, wherein The resonant sensor material comprises a self-assembled monolayer of material attached to at least the apex of the probe tip.

7. The scanning probe microscope according to claim 1, wherein The resonant sensor material is no thicker than 50 nm along the length of the probe tip in a direction parallel to the axis of the probe tip.

8. The scanning probe microscope according to claim 1, wherein The resonant sensor material includes a siloxane-containing material, and electromagnetic radiation from the light source generates at least one absorption resonance of the siloxane-containing material.

9. The scanning probe microscope according to claim 1, wherein The resonant sensor material is attached to the sample.

10. The scanning probe microscope according to claim 1, wherein The absorption resonance of the resonant sensor material has a wavelength within the infrared or visible light wavelength range.

11. A method for operating a scanning probe microscope, comprising the following steps: a cantilever driven by a metal probe tip of a scanning probe microscope, whereby the metal probe tip oscillates at least one material having a dielectric constant (ε) and the sample to make a connection; as a step of modulating a light source illuminating the connection between the probe tip and the sample with electromagnetic radiation, a resonant sensor material modulating the light source between the metallic probe tip and the sample surface, the resonant sensor material being attached to the probe tip; and as a step of detecting absorption of electromagnetic radiation by said resonant sensor material, the absorption of electromagnetic radiation by said resonant sensor material being dependent on the dielectric constant (ε) of at least one material of said sample to detect absorption of said electromagnetic radiation, The resonant sensor material has an absorption resonance within the wavelength range of the light source.

12. The scanning probe microscope operation method according to claim 11, wherein: The step of detecting absorption of the electromagnetic radiation includes the step of measuring a light-transmitting force or force gradient acting on the probe tip when coupled to the sample.

13. The scanning probe microscope operation method according to claim 11, wherein: The step of detecting absorption of the electromagnetic radiation includes the step of detecting, in the junction of the probe tip and the sample, the electromagnetic radiation scattered by a combination of the probe tip, the resonant sensor material, and the sample.

14. The scanning probe microscope operation method according to claim 11, wherein: The step of modulating the light source includes the step of modulating a tunable laser, the resonant sensor material having an absorption resonance within a wavelength range of the tunable laser.

15. The scanning probe microscope operation method according to claim 11, wherein: The resonant sensor material comprises a self-assembled monolayer of material attached to at least the apex of the probe tip.

16. The scanning probe microscope operation method according to claim 11, wherein: The resonant sensor material includes a siloxane-containing material, and modulating the light source includes modulating the light source to generate, when the electromagnetic radiation is generated, at a wavelength within at least one absorption resonance of the siloxane-containing material.

17. The scanning probe microscope operation method according to claim 11, wherein: Also includes: The step of coating said sample with said resonant sensor material.

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