Spontaneous and stimulated emission spectra for 124Xe35Cl molecules

Abstract

Abstract. The influence of the isotopic composition of active medium on a lasing spectrum of a XeCl laser has been investigated. Spectra of spontaneous and stimulated emissions for monoisotopic 124 Xe 35 Cl molecules were measured. The frequencies in lasing spectrum were determined. The frequencies of vibrational edging in the luminescence spectra of the molecule 124 Xe 35 Cl were also measured. We showed that varying the isotopic composition of the active medium one can get the lasing on frequencies different from the lasing ones in the natural XeCl laser. Keywords: excimer laser, isotopic composition, emission spectra, fine structure. Manuscript received 17.03.05; accepted for publication 18.05.05. 1. Introduction The electric discharge XeCl laser is one of the most powerful sources of coherent UV radiation now. This laser has wide applications for different scientific and technological branches. Many applications need for a narrow spectrum, whereas the XeCl laser spectrum is quite wide. It is well known that, under common lasing conditions and if there are no additional selecting elements, there are four electron-vibrational transitions: 0-0, 0-1, 0-2, and 0-3 in the vicinity of 308 nm. Different schemes were used for narrowing the lasing spectrum. Some papers reported that, under the low pressure of a working medium (0.3–0.5 atm), there is a line structure caused by rotation of molecules [1, 2]. While the frequency is tuned in a laser with the selective resonator, this structure becomes apparent at the high pressure (2-3 atm) [3], which makes the tuning discrete in the tuning range. The identification of the rotational spectrum of the XeCl laser has to be performed with taking into account the great number of overlapping lines from different rotational branches. One of the ways for simplification of the spectrum structure for its study is usage of mixtures enriched with isotopes [4]. Furthermore, usage of a mixture enriched by isotope, the concentration of which in the natural mixture is low, makes it possible to obtain new lasing lines. This paper shows spectra of luminescence and lasing for molecules