Tokue Ikuo, Nanbu Shinkoh
Department of Chemistry, Faculty of Science, Niigata University, 2-8050 Ikarashi, Niigata 950-2181, Japan.
J Chem Phys. 2006 Jun 14;124(22):224301. doi: 10.1063/1.2207611.
Transition probabilities were evaluated for the X (1)Sigma(+)-A (1)Pi system of AlNC and AlCN isomers to analyze photoabsorption and fluorescence spectra. The global potential energy surfaces (PESs) of the X (1)Sigma(+) and A (1)Pi (1 (1)A("),2 (1)A(')) electronic states were determined by the multireference configuration interaction calculations with the Davidson correction. Einstein's B coefficients were computed by quantum vibrational calculations using the three-dimensional PESs of these states and the electronic transition moments for the X-1 (1)A(") and X-2 (1)A(') systems. Einstein's B coefficients obtained for AlNC or AlCN exhibit that the Al-N or Al-C stretching mode is strongly enhanced in the transition. The absorption and fluorescence spectra calculated for the X-1 (1)A(") and X-2 (1)A(') systems are discussed comparing with the observed photoexcitation and fluorescence spectra. The lifetimes for the several vibrational levels of the A (1)Pi state were calculated to be ca. 7 ns for AlNC and 21-24 ns for AlCN from the fluorescence decay rates of the 1 (1)A(")-X and 2 (1)A(')-X emissions.
对AlNC和AlCN异构体的X(1)Σ⁺-A(1)Π体系的跃迁概率进行了评估，以分析光吸收和荧光光谱。通过带戴维森校正的多参考组态相互作用计算确定了X(1)Σ⁺和A(1)Π(1(1)A″,2(1)A′)电子态的全局势能面(PESs)。利用这些态的三维PESs以及X-1(1)A″和X-2(1)A′体系的电子跃迁矩，通过量子振动计算得到了爱因斯坦B系数。AlNC或AlCN的爱因斯坦B系数表明，在跃迁过程中Al-N或Al-C伸缩模式得到了强烈增强。讨论了X-1(1)A″和X-2(1)A′体系计算得到的吸收和荧光光谱，并与观测到的光激发和荧光光谱进行了比较。根据1(1)A″-X和2(1)A′-X发射的荧光衰减率，计算得到AlNC的A(1)Π态几个振动能级的寿命约为7 ns，AlCN的为21 - 24 ns。
