Boron Trifluoride: The Analysis of ν2 and the Determination of the Molecular Geometry

The parallel band ν2 of 10BF3 has been remeasured with a resolution of about 0.03 cm−1 and new values of the rotational constants have been determined. The values of B0 = 0.34474 ± 0.0005 (10BF3) and B0 = 0.34505 ± 0.0005 cm−1 (11BF3) are consistent with the geometry obtained in the electron-diffraction experiments of Kuchitsu and Konaka, but differ appreciably from the values previously reported by Nielsen. From our results we obtain r0 = 1.3096 ± 0.001 Å (10BF3), re = 1.3090 ± 0.001 Å (11BF3), and r0 = 1.3072 ± 0.002 Å (10BF3). From the analysis of the hot bands we have determined values of (B′ − B″) for ν4 and some of the anharmonic constants xss′.