Ultraviolet absorption in proton-irradiated solid deuterium

A broad absorption near a wavelength of 350 nm in proton-irradiated solid deuterium at 4.2 K has been measured. The absorption is caused by the resonant detrapping of localized electrons from their quantum bubbles. The growth and decay of the absorption with onset and termination of the proton beam is shown to be consistent with similar timing measurements on other spectroscopic features associated with the localized electrons. A simple square-well potential model is used to estimate the depth of the well and the size of the electron bubbles.