Tunnelling Measurements of Vibrational Spectra of Amino Acids and Related Compounds

Abstract

OBSERVATIONS of inelastic electron tunnelling in doped tunnel junctions have been used to study molecular Vibrational spectra of organic molecules including amino acids, fatty acids and related compounds. The potential of the technique as a spectroscopic tool in the analysis of trace amounts of chemical compounds has been explored through a systematic study of the spectra observed for a group of several dozen dopant chemicals. Previous observations of inelastic tunnelling spectra have been limited to a few simple organic acids and alcohols with high vapour pressures^1,2. In the experiments described here a system has been developed which allows the preparation of doped tunnel junctions using any reasonably stable chemical compound without danger of cross-contamination of the junction fabrication apparatus and permits the use of a wide range of successive dopants.