Determining thermodynamic temperature of sample surface based on area ratio of photoelectron spectrum

Abstract

The Fermi–Dirac (FD) distribution describes the occupancy of electronic states in a material at thermal equilibrium as a function of the thermodynamic temperature. By measuring the electron energy distribution using photoelectron spectroscopy, we can obtain the FD distribution and determine the thermodynamic temperature. This study proposes a method for determining the thermodynamic temperature, which involves calculating the area ratio between the photoelectron spectra above and below the Fermi level. This thermometric technique offers several advantages, including surface selectivity, noncontact measurement, and coordination with other measuring devices commonly used in surface analysis and nanoscale measurements under ultrahigh vacuum conditions. In this study, we measured the photoelectron spectra near the Fermi level on an Au (110) surface at three different temperatures: liquid nitrogen, liquid helium, and room temperatures. Using the area ratio method, we successfully determined the thermodynamic temperatures with an accuracy of less than 1 K.