New inelastic electron tunneling spectrometer with an absolute peak intensity

A new inelastic electron tunneling spectrometer with an absolute peak intensity is described. A smoothed second differential calculation is directly applied to high precision (7.5 digits) tunneling current-voltage data measured with Al/AlOx/Benzoic Acid/Pb tunnel junctions at 4.2 K. Interpolation and accumulation in addition to the above calculation permit high resolution and high signal-to-noise ratio inelastic electron tunneling (IET) spectra with absolute intensities. The half width at half maximum is 22 cm−1 and signal-to-noise ratio is more than 26 at 1598 cm−1 at the smoothing parameter M=19. The absolute peak intensities of tunnel junctions doped with solutions of different concentrations are measured easily and simply with this new method. The absolute peak intensities increase with an increase in both the solution concentration and dipping time. This method shows promise as a quantitative surface analytic system.