Systems and methods for non-destructive surface chemical analysis of samples

摘要

Aspects of the present invention include systems, devices, and methods of surface chemical analysis of solid samples, and particularly it relates to methods of chemical analysis of molecular compounds located either on or within thin surface layer of solid samples. Even more particularly, aspects of the present invention relate to systems, devices, and non-destructive methods combining both high sensitivity and high spatial resolution of analysis of chemical compounds located or distributed on the surface of solid samples with obtaining most important information regarding vibration spectra of atoms and molecular groups contained in thin surface layer of solid samples. These objectives are realized by implementation of computer-assisted systems that carefully regulate the motion of, and force applied to probes of atomic force microscopes.

主权项

1. A non-destructive method of surface chemical analysis of a sample, the method comprising the following steps:
(a) providing a device comprising a computer, a scanning probe microscope (SPM) operably linked with an optical spectrometer so that said device is capable of die following operations: (i) programmable switching while scanning of die sample's surface between at least two regimes of scanning probe microscope operation; (ii) relocating either the sample or a probe of said microscope for changing a position of said probe in any of three dimensions in each of said two regimes, said position of the probe defined relative to said sample; (iii) placing a tip of said probe at a first point on the surface of said sample and illuminating said sharp tip of said probe with a focused laser beam; (iv) collecting a light emitted from said surface proximate to said tip for spectrometric analysis provided by said optical spectrometer; and (v) storing in a memory of said computer both current coordinates of the probe and results of said spectrometric analysis obtained at said current coordinates; (b) initiating a first regime of said scanning probe microscope, said first regime including placing said tip located at the first point of the surface resulting in: (i) raising said tip off said surface normal to said surface fin the “Z dimension” or “Z axis′”), and (ii) keeping at least a predetermined minimum distance between said tip and said surface for preventing damage of either the tip or the sample; (c) moving either the probe or the sample to locate said tip of the probe over another point of the sample to be analyzed; (d) establishing a Z0-position of the probe relative to the sample, said Z0-position providing at least a minimum distance between said tip and the surface of the sample in proximity of said another point; (e) storing in said memory of said computer, the Z0-position established in step (d); (f) initiating a second regime of said scanning probe microscope, said second regime comprising such change in the Z-position of the probe such that the probe gets a new Z-position=Z0-position+ΔZ, wherein ΔZ is a non-zero parameter satisfying the following programmatically predetermined conditions: (i) said new Z-position is suitable for a tip enhanced Raman scattering of the light emitted from proximity of said tip than Z0-position, and (ii) said new Z-position results in no damage to both the tip and the sample; (g) illuminating said tip of said probe with said focused laser beam resulting in emission of light from the proximity of said sharp tip: (h) collecting the light emitted from tire proximity of said tip; (i) initiating data recording in said memory of said computer, said data obtained from spectrometric analysis of said light by said optical spectrometer, said recording continuing for a predetermined time interval; (j) storing in said computer memory both coordinates of the probe corresponding to said another point of analysis and data recording accumulated during step (i); and (k) returning to step (b) for providing surface chemical analysis in next at another point of the surface of the sample.