Kafader Jared O, Ray Manisha, Jarrold Caroline Chick
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
J Chem Phys. 2015 Aug 14;143(6):064305. doi: 10.1063/1.4928371.
The photoelectron (PE) spectrum of PrO(-) exhibits a short 835 ± 20 cm(-1) vibrational progression of doublets (210 ± 30 cm(-1) splitting) assigned to transitions from the 4f(2) [(3)H4] σ6s (2) Ω = 4 anion ground state to the 4f(2) [(3)H4] σ6s Ω = 3.5 and 4.5 neutral states. This assignment is analogous to that of the recently reported PE spectrum of CeO(-), though the 82 cm(-1) splitting between the 4f [(2)F2.5] σ6s Ω = 2 and Ω = 3 CeO neutral states could not be resolved [Ray et al., J. Chem. Phys. 142, 064305 (2015)]. The origin of the transition to the Ω = 3.5 neutral ground state is 0.96 ± 0.01 eV, which is the adiabatic electron affinity of PrO. Density functional theory calculations on the anion and neutral molecules support the assignment. The appearance of multiple, irregularly spaced and low-intensity features observed ca. 1 eV above the ground state cannot be reconciled with low-lying electronic states of PrO that are accessible via one-electron detachment. However, neutral states correlated with the 4f(2) [(3)H4] 5d superconfiguration are predicted to be approximately 1 eV above the 4f(2) [(3)H4] σ6s Ω = 3.5 neutral ground state, leading to the assignment of these features to shake-up transitions to the excited neutral states. Based on tentative hot band transition assignments, the term energy of the previously unobserved 4f(2) [(3)H4] σ6s Ω = 2.5 neutral state is determined to be 1840 ± 110 cm(-1).
PrO(-)的光电子（PE）能谱呈现出一个短的835±20 cm(-1)的双峰振动序列（分裂为210±30 cm(-1)），该序列对应于从4f(2) [(3)H4] σ6s (2) Ω = 4阴离子基态到4f(2) [(3)H4] σ6s Ω = 3.5和4.5中性态的跃迁。尽管CeO(-)最近报道的PE能谱中4f [(2)F2.5] σ6s Ω = 2和Ω = 3的CeO中性态之间82 cm(-1)的分裂无法分辨[Ray等人，《化学物理杂志》142, 064305 (2015)]，但该归属与CeO(-)的PE能谱归属类似。到Ω = 3.5中性基态的跃迁起始能量为0.96±0.01 eV，这就是PrO的绝热电子亲和能。对阴离子和中性分子的密度泛函理论计算支持了该归属。在基态上方约1 eV处观察到的多个、间隔不规则且强度较低的特征，无法与通过单电子脱离可及的PrO低能电子态相协调。然而，预计与4f(2) [(3)H4] 5d超组态相关的中性态比4f(2) [(3)H4] σ6s Ω = 3.5中性基态高约1 eV，导致将这些特征归属于向激发中性态的振激跃迁。基于初步的热带跃迁归属，确定之前未观察到的4f(2) [(3)H4] σ6s Ω = 2.5中性态的谱项能量为1,840±110 cm(-1)。
