ESR of matrix isolated bromine atoms produced in the H+Br2 reaction

The products of the H(D)+X2 reaction, where X is Br, Cl, or F, have been trapped in solid argon at 4 °K and observed via ESR. With Br2 as reactant the observed spectra are attributed to Br atoms electronically quenched in an axial crystal field. The spectra obtained using the other halogens were not clearly attributable to quenched atoms. The ESR of matrix-isolated Br atoms has not been observed previously, {While this paper was being reviewed, H. Muto and L. D. Kispert observed the ESR spectrum of partially quenched Br atoms in x-irradiated N-bromosuccinimide single crystals [J. Chem. Phys. 72, 2300 (1980)]} but their magnetic properties are similar to those recently observed by Iwasaki, Toriyama, and Muto for I atoms quenched in solid xenon. For Br: g⊥=2.646(1), g∥=1.55(1), ‖A⊥‖=1937(20) MHz, ‖A∥‖=423(10) MHz, and Q∥=100(10) MHz. Comparison was made with crude axial crystal field predictions derived using the magnetic parameters of the gas-phase atoms.