About the secondary electron emission from solid hydrogens: H 2, HD, D 2 and T 2

Abstract

Reported by Sørensen and Schou [H. Sørensen, J. Schou, J. Appl. Phys. 53 (1982) 5230], the electron-induced secondary electron emission yield curves, δ = f( E 0), of condensed hydrogen and deuterium show a significant isotopic effect with a yield for D 2 at about ∼1.5 times larger than that for H 2 and very low values ( δ < 0.1 at E 0 = 3 keV) in contrast to the very large yields ( δ > 50 at E 0 = 3 keV) reported, elsewhere, for condensed rare gases. Combined to the use of a recent model, physical considerations on the interaction of secondary electrons with zero point fluctuations permit to suggest a coherent explanation for these facts. The values of SE attenuation for three isotopes are deduced (∼4 nm for H 2; ∼5.6 nm for D 2; ∼4.9 nm for HD) and the electron-induced secondary electron emission yield curves, δ = f( E 0), initially limited to an investigated energy range, 0.5 keV < E 0 < 3 keV, are extrapolated down to their maximum values ranging from δ max ∼ 0.95 at E max 0 ∼ 145 eV, for H 2 to δ max ∼ 1.13 at E max 0 ∼ 175 eV for D 2. From the estimate of the attenuation length of secondary electrons, the same extrapolation procedure is also applied to solid tritium. Some consequences on charging of thick films and of small clusters are deduced. Showing also an isotopic effect, the expected evolution of X-ray-induced secondary electron emission yields, δ X = f( hν), of condensed H 2, HD, D 2 and T 2 are finally estimated.