Optical characteristics of the two-band barrier discharge excilamp on mercury monoiodide and mercury monobromide molecules

Abstract.

Introduction. An important direction in the development of excilamps is the study of working media emitting simultaneously several molecular bands of various exciplex molecules and or excimer molecules in the visible and ultraviolet spectral ranges in connection with possible applications in biotechnologies, medicine, and others.
Purpose. The aim of the research was to determine the optical characteristics of a two-band excilamp on mercury monoiodide and monobromide molecules, the working media of which is a barrier discharge plasma on a mixture of mercury diiodide vapor and mercury dibromide vapor with helium and a small admixture of molecular nitrogen.
Methods. The development of a gas-discharge plasma and excitation of the components of the working mixture was carried out by a pulse-periodic barrier discharge with a pulse repetition rate of 1-20 kHz, pulse duration was 150 ns.
Results. The ratio of the partial pressures of the components that give the maximum radiation yield at the wavelengths λmax== 502 nm and λmax== 444 nm, namely: HgI2:HgBr2:N2:He = 0.1 kPa: 0.5 kPa: 2 kPa: 180 kPa are revealed. The following are achieved: the specific average and pulsed radiation power of 12 mW / cm3 and 15.9 W / cm3, respectively, at a pulse repetition rate of 18 kHz, the efficiency of excilamp is ~ 15%. The long-term operation of the excilampi was detected (~ 107 pulses). Additional processes were found, that increase the population of the upper B2∑1/2+  -state of mercury monohalides in the gas-discharge plasma, which are: additional processes of excitation of mercury monobromide molecules (B2∑1/2+  -state)- the process of transfer of the population from the nitrogen molecule in metastable states of N2 (A3 ∑u+), as well as the excitation of radicals HgX (X2∑1/2+) by electrons in B2∑1/2+state of mercury monoiodide and mercury monobromide molecules.
Conclusion. The optical characteristics of a two-band barrier discharge excilamp on a mixture of mercury diiodide and mercury dibromide with helium and a small addition of molecular nitrogen are established. The radiation spectrum consists of the predominant radiation of two spectral bands of mercury monoiodide and mercury monobromide exciplex molecules, and low-intensity spectral bands of molecular nitrogen, lines of helium atoms and mercury. It is established the regularities in the change of the dependence in optical characteristics of plasma on repetition rate of the pump pulses of the discharge and quantitative composition of mixtures. These studies are of interest for the production of exciplex gas-discharge sources (excilamps) that simultaneously radiate two bands in a visible spectral range

Keywords: excilamp, halogen-containing molecules, mercury monoiodide and mercury monobromide, visible spectral range, barrier discharge

10.24144/2415-8038.2017.42.73-79