The high-resolution infrared spectrum of 10BF3 from 400 to 4600 cmK1

High-resolution infrared spectra of boron trifluoride, enriched to 99.5 at.% 10B, have been measured from 400 to 4600 cmK1. In that region we have identified and analyzed 17 absorption bands including three fundamentals. In addition, three hot bands associated with n2 were analyzed, seven hot bands associated with n4, two with n1Cn4 and one hot band each associated with the n3 and n1Cn2 bands. The spectral resolution of the measurements varied from 0.0015 cmK1 at the lowest wavenumber to 0.0035 cmK1 at the highest wavenumber. This study resulted in the first direct characterization of the n1 state via two routes, one through the combined analysis of the 110000–000000 and 110000– 100000 vibrational transitions and the other through the analysis of the 001100–000000 and 001100–100000 transitions. All of the quadratic vibrational anharmonic constants have been determined except x23. An improved set of ground state rotational constants has been determined for 10BF3. With corrections through most but not all of the quadratic rotational terms, we have found that BeZ0.346170G0.000003 cmK1 and CeZ0.173038G0.000006 cmK1. These give a B–F bond distance of reZ130.731G0.010 pm. The effects of l-type resonance were used to locate certain vibrational states that could not be directly observed through infrared transitions from the ground state. The splitting of the A0 1 and A0 2 components of n3Cn4 was found to be quite large, 6.131G0.007 cmK1. Several other resonances were also found including the weak vibrational interaction, which had been overlooked by earlier workers, between 2n2 and the A0 1 vibrational state of 3n4. q 2005 Elsevier B.V. All rights reserved.