Optical absorption microscopy and spectroscopy with nanometre resolution
Abstract
The first demonstration is presented of a new type of microscope, based on the scanning tunneling microscope (STM), that can record optical absorption spectra with nanometer (i.e., molecular) resolution. The starting point is conventional photothermal spectroscopy, in which the temperature rise due to the absorption of tunable monochromatic light is measured, giving a direct measurement of the absorption spectrum of a sample as a function of illuminating wavelength. The spatial resolution of such measurements is determined by the sizes of the pump beam or detector, whichever is smaller. The STM is used to measure the 'thermoelectric' tunneling voltage due to absorption. As the STM permits resolution of about 1 nm, and as the image is controlled by the thermal properties of the sample, the technique can image variations in the thickness of surface films and changes in subsurface characteristics, as well as chemical variations.
- Publication:
-
Nature
- Pub Date:
- December 1989
- DOI:
- 10.1038/342783a0
- Bibcode:
- 1989Natur.342..783W
- Keywords:
-
- Absorption Spectroscopy;
- Microscopes;
- Scanning Tunneling Microscopy;
- Spatial Resolution;
- Visible Spectrum;
- Absorption Spectra;
- Electron Tunneling;
- High Resolution;
- Thermocouples;
- Instrumentation and Photography