The B(1/2 2P3/2)→X(1/2 2Σ+) transition in XeBr

Abstract

The B(1/2 2P3/2)→X(1/2 2Σ+) transition in XeBr is recorded at high resolution, using a CCD array detector to record spectra from Tesla discharge sources containing isotopically pure 136Xe with 81Br2 or 79Br2. The high signal/noise capabilities of the detector permit the measurement of discrete vibrational structure in this system, which has normally been treated as a purely bound–free transition. The assignments comprise 119 υ′–υ″ bands for 136Xe81Br and 86 for 136Xe79Br, spanning υ′=0–33 and υ″=0–16. The van der Waals ground state is analyzed through fits to the customary polynomials in (υ+1/2) and to near-dissociation expansions. Franck–Condon calculations are used to locate the X-state potential on the internuclear axis relative to the B state, which is modeled as a Rittner potential. The following fundamental spectroscopic constants (units cm−1, for 136Xe81Br) are obtained from the analysis: Te′=35 863.2, ωe′=135.72, ωexe′=0.32, ωe″=25.7, ωexe″=0.62. The ground state has a dissociation energy 𝒟e″=254±2 cm−1 and supports 24 bound vibrational levels.

Interactions between anionic and neutral bromine and rare gas atoms

“…They were able to extract X1 / 2 and I3 / 2 potentials in the Morse-Morse-switching function-van der Waals form, by assuming that the third state II1 / 2 was unimportant ͓owing to the low population of Br * ͑ 2 P 1/2 ͒ in the beam͔ and, hence, that its potential could be set equal to that for the I3 / 2 state. 54 The present ESO potential provides very good agreement with that data, both for the dissociation energy and the vibrational constants. 54 The present ESO potential provides very good agreement with that data, both for the dissociation energy and the vibrational constants.…”

“…For collisions with Xe, the discrepancy with scattering potentials may seem significant, but in this case our potentials are supported by the superior emission spectroscopy data, 54 ͑vide supra͒ and by the transport calculations reported above. For collisions with Xe, the discrepancy with scattering potentials may seem significant, but in this case our potentials are supported by the superior emission spectroscopy data, 54 ͑vide supra͒ and by the transport calculations reported above.…”

Probing chemical dynamics with negative ions

“…While this experiment was inspired by the neutral ZEKE experiments first carried out by Muller-Dethlefs et al 90 and Muller-Dethlefs and Schlag, 91 the physics of anion ZEKE spectroscopy is quite different as it involves direct detachment to the continuum as opposed to pulsed-field ionization of high Rydberg states. 104,105 The covalent states of rare gas-halogen neutrals have also been probed in a series of scattering experiments, including differential cross sections measured in crossed molecular beam experiments by Lee and co-workers, 11,106-108 which yielded potentials for several RgX complexes, and integral cross section measurements by Aquilanti et al 109 The neutral interactions are also of interest because they are simple examples of open shell-closed shell interactions. 12,[99][100][101][102] The rare gas-halogen ͑RgX͒ complexes play a key role in excimer lasers, in which lasing takes place between the electronically excited, strongly bound charge transfer states and the repulsive wall of the weakly bound covalent ground states.…”

Interaction Potentials, Spectroscopy, and Transport Properties of the Br+−RG Systems (RG = He−Ar)

“…Interest in interactions involving the open-shell X( 2 P) neutrals arose independently in the 1970s after the detection of UV emission − and laser action − of the excited excimer states. Most of the emission measurements, however, tell us little about the lowest electronic states and even modern high-resolution spectroscopy has characterized quantitatively only a few of the heaviest Xe complexes (see, e.g., ref and references therein). More informative are the crossed molecular beam experiments pioneered by Lee and co-workers − and extended by the Perugia group (see, e.g., refs − ).…”