Photoemission from Amorphous Selenium

Photoemission yield measurements were made on amorphous selenium from about 6 to 21 eV. The yield curve exhibits a change in slope at about 7.8 eV corresponding to a maximum in the imaginary dielectric constant. The photoemission threshold is obtained by using a threshold law equation derived by Kane, Y = C (E − E_t)ⁿ, where Y is the yield, E and E_t are the photon energy and threshold energy, and C and n are constants. The yield data up to 8 eV are best represented by the equation with $\mathrm{n=}\frac{5}{2}$ resulting in an extrapolated photoemission threshold of 5.86 eV for amrophous selenium.