Optical characteristics of UV–VUV lamps on the electronic-vibrational transitions of the hydroxyl radical pumped by a nanosecond capacitive discharge

Abstract

This paper presents the results of a study of UV and VUV low-pressure lamp pumped by nanosecond capacitive discharge. This lamp works on the mixtures of helium and argon with water vapor (H2O) or ‘heavy’ water (D2O). At the capacitive low-pressure lamp emission spectra are mainly narrow band 308 nm OH (A–X) and large band in the VUV spectral range: 140–200 nm OH (C, B, A). Found, that the increasing the partial pressure of H2O and D2O (>130–150 Pa) led to a decrease in the intensity of VUV radiation of hydroxyl radicals. In the transition from He/H2O mixture to He/D2O mixture, the optimal pressure of helium is decreased. Reduced partial pressure of argon led to increased intensity of radiation of hydroxyl in the VUV range. The study of emission characteristics of OD* – lamps on a mixture of He/D2O and the OH* – lamps on a mixture of He/H2O showed that the intensity of the bands OD (X, C, A) is 1.5 times larger than the intensity of the bands OH (X, C, A). The maximum absolute intensity of UV–VUV radiation of the lamp (at a frequency of 1000 Hz) reached 1 W.