Knowledge Bank

Excitation of Rare Gas Solids (RGS) results in emission of molecular continua in vacuumultraviolet (VUV) and ultraviolet (UV) spectral regions. The well-known VUV band centered at 9.7 eV is attributed to the radiative decay of self-trapped excitons of molecular type $Ar\ast 2$. Origin of the UV continum centered at 6.2 eV is still under consideration. The paper reports new data on UV emission of solid Ar and give new assignment of this spectral feature. The samples with variable content of defects were grown in a special low temperature cell. Solid Ar was excited by low-energy electrons. The influence of oxygen-containing impurities was studied. Temperature dependence of the emission spectra and dose dependences at fixed temperatures were investigated. Glow curve of solid Ar was observed for the first time. Analysis of the glow curve assuming the first order kinetics was performed. UV and VUV emissions of solid Ar were measured as a function of electron trap concentration and the recombination of intrinsic molecular ions was established. Analysis of our results and comparison of those with the gas phase $data1,2$ permit us to suggest that UV emission of solid Ar is due to the decay of the molecular ions $Ar2++$. The data obtained reveal a new channel of electronically induced defect formation in RGS in addition to those founded $earlier3$.