Linear and Nonlinear Spectroscopy with the Tunable AC Scanning TunnelingMicroscope

摘要

The tunable microwave frequency AC scanning tunneling microscope (ACSTM) hasopened the possibility of recording local spectra and local chemical information on insulator surfaces much as the conventional STM has done for metals and semiconductors. We describe the various types of spectroscopies that can be performed with the ACSTM. These include linear spectroscopies where the amplitude at the modulation frequency is measured as well as nonlinear spectroscopies utilizing the amplitudes of the harmonics of the modulation frequency generated in the tunneling junction. Spectroscopy in the microwave frequency range also enables heretofore unrealizable measurements on conducting substrates such as the rotational spectroscopy of a single adsorbed molecule.