Abstract
The threshold of secondary electrons in photoelectron yield spectroscopy (PYS) was examined using numerical calculations based on Fowler's formula, and was measured on a Cu(111) surface as a function of the surface temperature. In the numerical calculations, the yields are affected by surface temperature at around the threshold. The yield to the power of 1/2 shows a linear relationship of over 0.04 eV per 100 K from the threshold as a function of energy. The estimated threshold shifts to a lower energy with increasing surface temperature, by 0.003 eV per 100 K. The estimated thresholds also decrease with increasing value of the multiplier of n in Fowler's formula. In experiments, the threshold of Cu(111) at room temperature is estimated to be 4.8 eV±0.05 eV. The amount of change in the threshold caused by variation in surface temperature is interpreted in terms of the effects of the intrinsic Fowler's formula and lattice expansion.
