Chemical mapping using thermal microscopy at the micro and nano scales

Abstract

A non-destructive method for chemical imaging with ˜1 nm to 10 μm spatial resolution (depending on the type of heat source) without sample preparation and in a non-contact manner. In one embodiment, a sample undergoes photo-thermal heating using an IR laser and the resulting increase in thermal emissions is measured with either an IR detector or a laser probe having a visible laser reflected from the sample. In another embodiment, the infrared laser is replaced with a focused electron or ion source while the thermal emission is collected in the same manner as with the infrared heating. The achievable spatial resolution of this embodiment is in the 1-50 nm range.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . A system for photo-thermal spectroscopic imaging, comprising:
 a confocal microscope;   a diffraction-limited photo-thermal microscope comprising an infrared light detector;   a sub-diffraction-limited photo-thermal microscope comprising a visible light detector; and   means for moving a sample perpendicular to the surface of the sample to maximize the dc component of the visible probe which is used to reconstruct the topography of the sample;   wherein the sample is photo-thermally heated using an infrared laser and the resulting increase in thermal emissions is measured using the sub-diffraction-limited photo-thermal microscope.   
     
     
         2 . The system of  claim 1 , wherein the system is non-contact and requires no sample preparation. 
     
     
         3 . The system of  claim 1 , wherein the system has a spatial resolution of between about 1 and 10 μm. 
     
     
         4 . A system for photo-thermal spectroscopic imaging, comprising:
 a confocal microscope;   a diffraction-limited photo-thermal microscope comprising an infrared light detector;   a sub-diffraction-limited photo-thermal microscope comprising a visible light detector; and   an interferometer to maximize a signal from the visible probe;   wherein a sample is photo-thermally heated using an infrared laser and the resulting increase in thermal emissions is measured using the sub-diffraction-limited photo-thermal microscope.   
     
     
         5 . The system of  claim 4 , wherein the system is non-contact and requires no sample preparation. 
     
     
         6 . The system of  claim 4 , wherein the system has a spatial resolution of between about 1 and 10 μm. 
     
     
         7 . A system for photo-thermal spectroscopic imaging, comprising:
 a confocal microscope;   a diffraction-limited photo-thermal microscope comprising an infrared light detector;   a sub-diffraction-limited photo-thermal microscope comprising a visible light detector; and   an interferometer to maximize a signal from the visible probe;   wherein a sample is photo-thermally heated using an infrared laser and the resulting increase in thermal emissions is measured using the sub-diffraction-limited photo-thermal microscope, and wherein either a moving mirror arm of the interferometer or the sample are dithered at a higher frequency than a periodic heating to eliminate a varying photo-thermal signal.   
     
     
         8 . The system of  claim 7 , wherein the system is non-contact and requires no sample preparation. 
     
     
         9 . The system of  claim 7 , wherein the system has a spatial resolution of between about 1 and 10 μm.