ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Electron transmission spectroscopy (ETS) and bound-state and continuum multiple-scattering Xα (MS-Xα) calculations are employed to characterize the unoccupied a′2, a′1 and e′ orbitals of BF3 and BCl3. The a′2 orbital of BF3, which produces a peak about 7 eV below threshold in the x-ray absorption spectrum (XAS), generates a scattering resonance at 3.5 eV in ETS. Similarly, the e′ orbital that lies about 2 eV above threshold in XAS occurs about 13-16 eV above threshold in ETS. Dissociation of F- from BF3 due to electron attachment is attributed to a core-excited shape resonance involving an e″ → a″2 excitation and electron capture into the a′2 orbital. In BCl3 all the unoccupied orbitals lie at lower energy than in BF3 and are closely spaced, making definitive spectral assignments difficult. Both Hartree-Fock (HF) and MS-Xα methods apparently underestimate the stability of the unoccupied e′ orbital of BCl3. Vibronic coupling due to out-of-plane bending may significantly affect the spectral intensities. Feshbach resonances are observed for BCl3 at energies close to those observed in the vacum-UV absorption spectrum. The lower energies of the unoccupied orbitals of BCl3 are consistent with their stronger bonding to nucleophiles.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560290510
