Observation of a forbidden infrared transition in 11BF3

On the determination of C0 (or A0), , and some dark states for symmetric-top molecules from infrared spectra without the need for localized perturbations

“…One such forbidden band, m 14 or 14 1;1 0;0 , has been observed for cyclopropane. That transition has Dk = ±2, Dl = Ç1 selection rules as was found for a similar transition observed in 11 BF 3 [22].…”

The analysis of combination and overtone states of 11BF3 from 1650 to 4600cm−1

“…The spectra were analyzed using the same non-linear least-squares computer program that was used in our earlier work on BF 3 [1][2][3][4] as well as on the analysis of the var- Table 1 Experimental parameters describing the spectra used in this analysis, but not included in Ref. [ ious isotopomers of SO 3 [8,9].…”

“…The vibrational level notation, ðv 1 ; v 2 ; v 3 l 3 ; v 4 l 4 Þ l , where l = l 3 + l 4 , is the same as that used by the authors in the previous publications on SO 3 and BF 3 . We have found this notation useful, especially in describing levels where quanta of both m 3 and m 4 are excited.…”

“…In this paper, we will conclude our investigation of the BF 3 isotopomers with the analysis of 11 BF 3 for states that lie above 1650 cm À1 . Previous investigations [5] in this region were performed at moderate resolution ($0.03-0.05 cm À1 ) and were able to only partially resolve rotational structure, thus obtaining estimated band origins through contour analysis.…”

“…We have recently published a series of papers [1][2][3][4] detailing the analysis of high-resolution infrared and Raman spectra of both 10 BF 3 and 11 BF 3 (D 3h ). Highlights of these studies include: (1) analysis of all of the fundamental vibrational modes of both 10 BF 3 and 11 BF 3 ; (2) determination of nearly all of the quadratic vibrational anharmonic terms for 10 BF 3 based on the analysis of thirty vibrational bands; (3) direct characterization of the m 1 symmetric stretching, infrared-inactive state of both isotopomers through the use of difference bands; (4) confirmation of the counterintuitive result of the infrared study that the m 1 symmetric stretching frequency is 0.2 cm À1 higher for 11 BF 3 than for 10 BF 3 by direct examination of m 1 using CARS spectroscopy; (5) observation in 11 BF 3 of the forbidden 011 1 0 0 À 000 0 0 0 E 00 -A 0 1 transition, which becomes infrared-active because of the Coriolis mixing of dipole moment derivative terms.…”