Spectrophotometer utilizing a solid state source of radiant energy having a controllable frequency spectra characteristic

摘要

A solid state source of radiant energy having a characteristic frequency spectra with a high frequency cutoff nu co, which is a function of the applied voltage value. The source is a metal-insulator-metal tunnel junction wherein the insulator layer is relatively thin with respect to the metal layers and inelastic tunneling occurs. To facilitate output coupling to surface plasmon modes in the junction, the counter-electrode metal layer, from which the radiant energy is emitted, is roughened. One of the uses for the solid state source is as a light source of a spectrophotometer where the transmittance or reflectance band characteristics of a sample are determined by converting the photodetector current to its second derivative and correlating the second derivative with the applied voltage which is modulated over a predetermined range of amplitude values.