Electron Mobilities and Ranges in Solid Neopentane: Effect of Liquid–Solid Phase Change

Abstract

The mobility of thermal electrons, the radiolysis free ion yield, and the penetration range of epithermal electrons in neopentane increase on going from the liquid to the solid phase at the triple point (257 K). The mobility is u = 71 cm2/V s in the liquid at 258 K and 154 cm2/V s in the solid at 257 K; the density normalized penetration range of the secondary electrons in X-radiolysis is bGPd = 1.25 × 10−6 g/cm2 in the liquid (296−258 K) and 1.72 × 10−6 g/cm2 in the solid (253−202 K). The increases at the triple point are presumably due to the greater degree of order in the solid. Electron mobility in the solid increases with decreasing temperature, u(solid) ≈ 6.8 × 105T−3/2 cm2/V s. The scattering length of neopentane is ∼8 Å in the solid and ∼9 Å in the liquid near the triple point.