Electronic Spectroscopy of B Atoms and B2 Molecules Isolated in Para-H2, Normal-D2, Ne, Ar, Kr, and Xe Matrices
Abstract
We report spectroscopic observations on B atoms isolated in cryogenic parahydrogen (pH2), normal deuterium (nD2), Ne, Ar, Kr, and Xe matrices, and of B2 molecules in Ne, Ar, Kr, and Xe matrices. The 2s(sup 2)3s((sup 2)S) left arrow 2s(sup 2)2p((sup 2)P) B atom Rydberg absorption suffers large gas-to-matrix blue shifts, increasing from +3000 to +7000/cm in the host sequence: Xe <Kr < Ar approx. = Ne approx. =nD(2) approx. = pH2. Much smaller shifts are observed for the 2s2p(sup 2)((sup 2)D) left arrow 2s(sup 2)2p((sup 2)P) B atom core-to-valence transition. We assign pairs of absorption peaks spaced by approx. 10 nm in the 315 to 355 nm region to the B2 (A (sup 3)Sigma (sub u)(-) left arrow X (sup 3)Sigma(sub g)(-)) Douglas-Herzberg transition. We assign a much weaker progression in the 260 to 300 nm region to the B2 (2) (sup 3)Pi(sub u) left arrow X (sup 3)Sigma(sub g)(-) transition. We report a novel progression of strong peaks in the 180 to 200 nm region which we suspect may be due to B2 molecules, but which remains unassigned. Ultraviolet (UV) absorption spectra of B/pH2 solids show two strong peaks at 216.6 and 208.9 nm, which we assign to the matrix perturbed 2s(sup 2)3s((sup 2)S) left arrow 2s(sup 2)2p((sup 2)P) and 2s2p(sup 2)((sup 2)D) left arrow 2s(sup 2)2p((sup 2)P) B atom absorptions, respectively. This assignment is supported by quantum path integral simulations of B/pH2 solids reported in the following article in this journal J.R. Krumrine, S. Jang, G.A. Voth, and M.H. Alexander, J. Chem. Phys. XXX, yyyy (zzzz). Laser induced fluorescence emission spectra of B/pH2 solids show a single line at 249.6 nm, coincident with the gas phase wavelength of the 2s(sup 2)3s((sup 2)S) right arrow 2s(sup 2)2p((sup 2)P) B atom emission. The UV laser irradiation results in photobleaching of the B atom emission and absorptions, accompanied by the formation of B2H6.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 15, 2000
- Accession Number
- ADA408930
Entities
People
- Mario E. Fajardo
- Michel Macler
- Michelle E. Derose
- Simon Tam
Organizations
- Air Force Research Laboratory