Changes in site-specific shape resonances in nitrogen K-shell photoionization of N2O induced by vibrational excitation
Changes in site-specific shape resonances in nitrogen K-shell photoionization of N2O induced by vibrational excitation
复制标题
振动激发引起的 N2O 氮 K 壳光电离中位点特定形状共振的变化
DOI：
10.1088/1361-6455/aaaeb3
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
R. R. Lucchese
中科院分区：
文献类型：
--
作者：
M. Hoshino;H. Kato;N. Kuze;H. Tanaka;H. Fukuzawa;K. Ueda;R. R. Lucchese
在~ 300和~ 630 K温度下，在σ形共振能区测量了氮2o分子的中心（N c）和末端（N t）氮K壳层光电子能谱（PESs）。根据玻尔兹曼分布估计了这些温度下的振动居群，提取了初始电子基态的振动基态和弯曲激发能级的ps。通过对核孔态振动能级上的ps积分，得到了振动基底能级和弯曲激发能级电离的振动积分部分截面和不对称参数作为入射光子能量的函数。在N - c光电离中，弯曲激发能级的形状共振转移到光子能量较低的一侧，并且比地面振动能级的形状共振窄。从弯曲激发能级出发的N - t光电离，共振的下移比N - c电离更明显。这些实验结果与理论预测在质量上是一致的，并且表明与N - t核孔相关的形状共振比与N - c核孔相关的形状共振对初始状态弯曲角更敏感。然而，在本文研究的光子能量范围内，k壳层光电离通道的弯曲激发能级的不对称参数与地面振动能级的不对称参数表现出几乎相同的行为。
The central (N c) and terminal (N t) nitrogen K-shell photoelectron spectra (PESs) of N 2 O molecules have been measured in the σ shape resonance energy region at temperatures of∼ 300 and∼ 630 K. Estimating vibrational populations based on the Boltzmann distribution at these temperatures, PESs of vibrationally ground and bending-excited levels in the initial electronic ground state were extracted. Vibrationally integrated partial cross sections and asymmetry parameters for ionization from vibrationally ground and bending-excited levels were obtained as a function of the incident photon energy by integrating PESs over the vibrational levels of the core-hole states. In N c photoionization, the shape resonance from the bending-excited level was found to be shifted to the lower photon energy side and to become narrower than that from the ground vibrational level. In N t photoionization from the bending-excited level, the downward shift of the resonance is more significant than that in N c ionization. These experimental findings are qualitatively consistent with theoretical predictions and suggest that the shape resonance associated with the N t core hole is more sensitive to the bending angle of the initial state than is the shape resonance associated with the N c core hole. The asymmetry parameters for photoionization from the bending-excited level, however, showed almost the same behavior as those from the ground vibrational level for both K-shell photoionization channels and in the photon energy range studied here.