ANALYSIS OF HIGH-RESOLUTION INFRARED SPECTRA OF $^{11}$BF$_3$
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Date
2005
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Publisher
Ohio State University
Abstract
We have been engaged in the measurement and analysis of high-resolution infrared spectra of enriched samples of $^{11}$BF$_3$. The Bruker IFS 120HR Fourier transform spectrometer at the Pacific Northwest National Laboratory (PNNL) facilities has been used to obtain measurements that range in resolution from 0.0015 to 0.0035 cm$^{-1}$ with pathlengths of up to 32 m. The fundamental infrared active transitions and many hot bands, overtones and combination bands have been investigated. A multiple reflection White cell was used to identify a number of weak states not directly visible from the ground state. One of these states, 3$\nub{4}$, visible as the hot band 3$\nub{4}$ $- $2$\nub{4}$, is involved in a strong Fermi resonance with the $\nub{3}$ fundamental and was directly measured for the first time. A rotational perturbation was found to couple the 2$\nub{2}$ and $\nub{1}$ $+$ $\nub{4}$ vibrations through a $\Delta${\em K} $=2$, $\Delta${\em l} $=-1$ interaction constant. The infrared inactive $\nub{1}$ symmetric-stretching mode was characterized by two independent routes, one using the transitions (110$^{0}$0$^{0}$) $-$ (000$^{0}$0$^{0}$), A$_2^{\prime\prime }$ $-$ A$_1^{\prime }$ and (110$^{0}$0$^{0}$) $-$ (100$^{0}$0$^{0}$), A$_2^{\prime\prime }$ $-$ A$_1^{\prime }$, and the other using the transitions (001$^{1}$0$^{0}$) $- $(000$^{0}$0$^{0}$), E$^{\prime }$ $-$ A$_1^{\prime }$ and (001$^{1}$0$^{0}$) $-$ (100$^{0}$0$^{0}$), E$^{\prime }$ $-$ A$_1^{\prime }$. Since the rovibrational parameters for the $\nub{1}$ state are not equilibrium parameters (not parameters from the bottom of the potential well), they are slightly different for $^{11}$BF$_3$ and $^{10}$BF$_3$. Rovibrational constants will be presented for a number of combination/overtone states as well as the Hamiltonian used to derive them.
Description
Author Institution: Pacific Northwest National Laboratory, P.O. Box 999, Mail Stop K8-88, Richland, WA 99352 (PNNL is operated for the US; Department of Energy by the Battelle Memorial Institute under contract DE-AC05-76RLO 1830); 15012 24th Ave. S.E., Mill Creek WA, 98012