Grimminger Robert, Sheridan Phillip M, Clouthier Dennis J
Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA.
Department of Chemistry and Biochemistry, Canisius College, Buffalo, New York 14208, USA.
J Chem Phys. 2014 Apr 28;140(16):164302. doi: 10.1063/1.4871010.
We have studied the B̃ (2)A1-X̃ (2)B2 laser-induced fluorescence (LIF) spectrum of the jet-cooled F2BO radical for the first time. The transition consists of a strong 0(0)(0)band at 446.5 nm and eight weak sequence bands to shorter wavelengths. Single vibronic level emission spectra obtained by laser excitation of individual levels of the B̃ state exhibit two electronic transitions: a very weak, sparse B̃-X̃ band system in the 450-500 nm region and a stronger, more extensive set of B̃ (2)A1-à (2)B1 bands in the 580-650 nm region. We have also performed a series of high level ab initio calculations to predict the electronic energies, molecular structures, vibrational frequencies, and rotational and spin-rotation constants in the X̃ (2)B2, à (2)B1 and B̃ (2)A1 electronic states as an aid to the analysis of the experimental data. The theoretical results have been used as input for simulations of the rotationally resolved B̃ (2)A1-X̃ (2)B2 0(0)(0) LIF band and Franck-Condon profiles of the LIF and single vibronic level emission spectra. The agreement between the simulations obtained with purely ab initio parameters and the experimental spectra validates the geometries calculated for the ground and excited states and the conclusion that the radical has C2v symmetry in the X̃, Ã, and B̃ states. The spectra provide considerable new information about the vibrational energy levels of the X̃ and à states, but very little for the B̃ state, due to the very restrictive Franck-Condon factors in the LIF spectra.
我们首次研究了喷射冷却的F2BO自由基的B̃ (2)A1-X̃ (2)B2激光诱导荧光（LIF）光谱。该跃迁由位于446.5 nm处的强0(0)(0)带和八个向较短波长的弱序列带组成。通过对B̃态的各个能级进行激光激发获得的单振动能级发射光谱显示出两个电子跃迁：在450 - 500 nm区域有一个非常弱、稀疏的B̃-X̃带系，以及在580 - 650 nm区域有一组更强、更广泛的B̃ (2)A1-Ã (2)B1带。我们还进行了一系列高水平的从头算计算，以预测X̃ (2)B2、Ã (2)B1和B̃ (2)A1电子态的电子能量、分子结构、振动频率以及转动和自旋 - 转动常数，以辅助分析实验数据。理论结果已用作模拟转动分辨的B̃ (2)A1-X̃ (2)B2 0(0)(0) LIF带以及LIF和单振动能级发射光谱的弗兰克 - 康登分布的输入。使用纯从头算参数获得的模拟结果与实验光谱之间的一致性验证了为基态和激发态计算的几何结构，以及该自由基在X̃、Ã和B̃态具有C2v对称性的结论。这些光谱提供了关于X̃和Ã态振动能级的大量新信息，但由于LIF光谱中非常受限的弗兰克 - 康登因子，关于B̃态的信息很少。
