Photochemical dynamics of 79Br2 in Xe matrices

Publisher Website
Google Scholar
Abstract
The photochemical dynamics of Br2 trapped in a Xe matrix have been investigated. Following excitation into either the B 3Π(0+u) or 1Π(1u) states, emission occurs in the far red and infrared region. Analysis of the emission allows the emitting states to be characterized as B 3Π(0+u) v′ = 0→X 1Σ+g, and (tentatively) the A′ 3Π(2u)→X1Σ+g. The spectrum of the B→X emission was recorded and exhibited unusually broad vibronic emission lines when compared with Ar spectra. The B→X emission lifetime was measured to be 3.6±0.5 μs and is in excellent agreement with the expected value for the radiative lifetime. The risetime of the B signal was found to be limited by the detection system (∼15 ns). The tentatively identified A′→X emission has a lifetime of 4±1 ms. The A3Π(1u)→X 1Σ+g emission resolved clearly in Ar and Kr matrices is altogether absent from Br2 isolated in Xe. Experiements were performed to measure the relative intensities of the B/A′ emissions in Xe and compare them with earlier results from Ar matrices. The Xe B/A′ ratio was found to be nearly 100 times greater in Xe then in Ar. The observations were found to be independent of temperature from 12 to 60 K and independent of concentrations from 1:500 to 1:10 000, Br2 in Xe.