Liu Jinjun, Chen Ming-Wei, Melnik Dmitry, Yi John T, Miller Terry A
Department of Chemistry, Laser Spectroscopy Facility, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210, USA.
J Chem Phys. 2009 Feb 21;130(7):074302. doi: 10.1063/1.3072104.
New experimental data have been obtained for the methoxy radical by observing at high-resolution laser-induced fluorescence (LIF) and stimulated emission pumping (SEP) transitions between the X (2)E and lowest excited A (2)A(1) state. The SEP transitions were from the A state (pumped from the X (2)E(3/2) spin-orbit component) to the X (2)E(1/2) spin-orbit component. These data for the first time directly connect with high precision the spin-orbit components of the X (2)E ground state of CH(3)O. Surprisingly these new SEP observations are inconsistent with predictions of the X state structure based on long-standing analyses primarily based on the microwave spectra of ground state CH(3)O. It is found that all the experimental data can be understood consistently when the previously accepted value of the spin-orbit coupling constant is adjusted and the reflection parity assignments in the X state are reversed. The latter action changes the sign of a number of reflection-parity-dependent parameters in the X state. The ramifications of the changes and the physical interpretation of the resulting parameters are discussed in some detail.
通过在高分辨率激光诱导荧光（LIF）和受激发射泵浦（SEP）下观测X (2)E和最低激发态A (2)A(1)之间的跃迁，已获得了关于甲氧基自由基的新实验数据。SEP跃迁是从A态（从X (2)E(3/2)自旋轨道分量泵浦）到X (2)E(1/2)自旋轨道分量。这些数据首次高精度地直接关联了CH(3)O的X (2)E基态的自旋轨道分量。令人惊讶的是，这些新的SEP观测结果与基于长期以来主要基于基态CH(3)O微波光谱分析所预测的X态结构不一致。研究发现，当调整自旋轨道耦合常数的先前公认值并反转X态中的反射宇称分配时，所有实验数据都能得到一致的解释。后一操作改变了X态中许多与反射宇称相关参数的符号。详细讨论了这些变化的影响以及所得参数的物理解释。
