Yang Zheng, Hrovat David A, Hou Gao-Lei, Borden Weston Thatcher, Wang Xue-Bin
Physical Sciences Division , Pacific Northwest National Laboratory , P.O. Box 999, MS K8-88 , Richland , Washington 99352 , United States.
Department of Chemistry and the Center for Advanced, Scientific Computing and Modeling , University of North Texas , 1155 Union Circle, #305070 , Denton , Texas 76203-5070 , United States.
J Phys Chem A. 2019 Apr 11;123(14):3142-3148. doi: 10.1021/acs.jpca.8b11063. Epub 2019 Mar 27.
Negative ion photoelectron (NIPE) spectra, with 193, 266, 300, and 355 nm photons, of the radical anion of 1,8-naphthoquinone (1,8-NQ) have been obtained at 20 K. The electron affinity of 1,8-NQ is determined from the first resolved peak in the NIPE spectrum to be 2.965 ± 0.005 eV. Franck-Condon factors (FCFs), calculated from the CASPT2/aug-cc-pVDZ optimized geometries, normal modes, and vibrational frequencies, successfully simulate the intensity and frequencies of the spectral features that are associated with the lowest two electronic states. The NIPE spectra of 1,8-NQ and the peak assignments, based on the computed FCFs, confirm the theoretical predictions that A is the ground state of 1,8-NQ and B is the first excited state. The spectra provide an experimental value of Δ E = -0.6 kcal/mol, which is 2 kcal/mol smaller in magnitude than the (12/12)CASPT2/aug-cc-pVTZ calculated value of Δ E = -2.6 kcal/mol.
在20K温度下，利用193、266、300和355nm的光子，获得了1,8-萘醌（1,8-NQ）自由基阴离子的负离子光电子（NIPE）光谱。根据NIPE光谱中第一个分辨出的峰，确定1,8-NQ的电子亲和能为2.965±0.005eV。通过CASPT2/aug-cc-pVDZ优化的几何结构、简正模式和振动频率计算得到的弗兰克-康登因子（FCFs），成功地模拟了与最低两个电子态相关的光谱特征的强度和频率。基于计算得到的FCFs，1,8-NQ的NIPE光谱和峰归属证实了理论预测，即A是1,8-NQ的基态，B是第一激发态。光谱提供了ΔE=-0.6kcal/mol的实验值，其绝对值比(12/12)CASPT2/aug-cc-pVTZ计算得到的ΔE=-2.6kcal/mol小2kcal/mol。
