The F2BO free radical is a known, although little studied, species but similar X2BY (X = H, D, F; Y = O, S) molecules are largely unknown. High level ab initio methods have been used to predict the molecular structures, vibrational frequencies (in cm-1), and relative energies of the ground and first two excited electronic states of these free radicals, as an aid to their eventual spectroscopic identification. The chosen theoretical methods and basis sets were tested on F2BO and found to give good agreement with the known experimental quantities. In particular, complete basis set extrapolations of coupled-cluster single and doubles with perturbative triple excitations/aug-cc-pVXZ (X = 3, 4, 5) energies gave excellent electronic term values, due to small changes in geometry between states and the lack of significant multireference character in the wavefunctions. The radicals are found to have planar C2v geometries in the 2B2 ground state, the low-lying 2B1 first excited state, and the higher 2A1 state. Some of these radicals have very small ground state dipole moments hindering microwave measurements. Infrared studies in matrices or in the gas phase may be possible although the fundamentals of H2BO and H2BS are quite weak. The most promising method of identifying these species in the gas phase appears to be absorption or laser-induced fluorescence spectroscopy through the allowed B̃-X̃ transitions which occur in the visible-near UV region of the electromagnetic spectrum. The ab initio results have been used to calculate the Franck-Condon profiles of the absorption and emission spectra, and the rotational structure of the B̃-X̃000 bands has been simulated. The calculated single vibronic level emission spectra provide a unique, readily recognizable fingerprint of each particular radical, facilitating the experimental identification of new X2BY species in the gas phase.

Document Type


Publication Date


Notes/Citation Information

Published in The Journal of Chemical Physics, v. 141, no. 24, article 244309, p. 244309-1 through 244309-9.

Copyright 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

The following article appeared in Published in The Journal of Chemical Physics, v. 141, no. 24, article 244309, p. 1-9 and may be found at http://dx.doi.org/10.1063/1.4904290

Digital Object Identifier (DOI)


Funding Information

This research was supported by the National Science Foundation.

1.eps (1571 kB)
Fig. 1 High-Resolution

Figure 1.pptx (73 kB)
Fig. 1 Powerpoint

2.eps (1979 kB)
Fig. 2 High-Resolution

Figure 2.pptx (86 kB)
Fig. 2 Powerpoint

3.eps (2063 kB)
Fig. 3 High-Resolution

Figure 3.pptx (98 kB)
Fig. 3 Powerpoint

4.eps (2707 kB)
Fig. 4 High-Resolution

Figure 4.pptx (117 kB)
Fig. 4 Powerpoint

5.eps (20394 kB)
Fig. 5 High-Resolution

Figure 5.pptx (92 kB)
Fig. 5 Powerpoint

Table I.GIF (42 kB)
Table I

Table II.GIF (43 kB)
Table II

Table III.GIF (47 kB)
Table III

Table IV.GIF (50 kB)
Table IV

Included in

Chemistry Commons