New interpretation of the third rare-gas excimer continua

Abstract

Time correlated optical emission spectra of argon, krypton and xenon in the wavelength range from 110 to 450 nm, and 0 to 6000 ns time interval, recorded at the Munich Tandem accelerator using heavy ion beam excitation with 2 ns beam pulses, were measured in order to clarify the origin of the so called third rare gas excimer continua. Experiments were performed at xenon and krypton pressures between 50 and 250 mbar, and argon pressures between 230 and 1500 mbar. All spectra clearly show different distinct peaks, emerging at different time delays after excitation. These spectral maxima are interpreted as arising from excimer emissions by separate radiating species, formed by gas kinetic processes. While the spectral shape of the components, forming the third continuum radiation in the heavy rare gases krypton and xenon turned out to be of complicate structure, in the case of argon all wavelength spectra could be reproduced by fitting a limited number of Gaussian functions with fixed center wavelengths and fixed widths to the data. Hereby, six distinct maxima, appearing at four different times after the excitation pulse, could be identified.