Interference effects in the infrared absorption of solid hydrogen due to localized electrons

Abstract

Recent experiments on proton-irradiated solid hydrogen show a broad absorption in the spectral region 4000–8000 cm−1. This broad absorption has been interpreted as being due to the lowest bound-state transition of electrons localized in cavitylike states in the lattice. Superposed on this broad spectrum is an asymmetric line, which is centered around the Stark-shifted fundamental vibrational transition (ν = 0 → ν = 1) of the molecules in the nearest neighbour positions with respect to the localized center of the electron. We present a detailed calculation of this line shape and show that the asymmetry can be attributed to the interference between the dipole of the localized electron and the charge-induced molecular dipole, as a result of a coincidence in the energies of the molecular and the electronic transitions.