Spectroscopic Study of a Kr and Kr/Cl2 Excilamps Under Sinusoidal and Pulsed Excitation

Abstract

Recently considerable attention focused on the development of excimers and exciplexe lamp. These lamps are sources of spontaneous radiation based on the transitions of excited molecules called excimers when pure noble gas or a mixture of several noble gases is added. The excited molecules are considered to be exciplex when the gas mixture contains one or more halogens in addition to noble gases or mercury. The de-excitation of these molecules to their dissociative fundamental states induces a loss of energy in the form of UV, visible and IR radiation. The work is based on an experimental study of a pure krypton lamp and theoretical study of the Kr/Cl2 plasma chemistry in terms of the homogenous model. The lamp is excited by a dielectric barrier discharge, the gas breakdown is obtained between two flat and identical electrodes of 5 cm × 5 cm surface area, these electrodes are insulated and separated by two dielectric plates of permittivity 4 and thickness 2 mm. The space between the two dielectrics is 2 mm and is filled with gas at pressure of 129 to 460 mbar. In order to carry out a parametric study, the influence of several parameters such as applied voltage, frequency and gas pressure was studied. A spectroscopic and kinetic analysis of a pure krypton and Kr/Cl2 mixture excilamp excited by DBD is reported here. The interpretation of the experimental and theoretical results allowed to explain chemical processes responsible of the production of excimers inducing UV emission and to link these processes to the IR emissions that control the population of the excited metastable states of krypton. These states are indirectly responsible for UV emission.