Huang Dao-Ling, Liu Hong-Tao, Ning Chuan-Gang, Wang Lai-Sheng
Department of Chemistry, Brown University, Providence, Rhode Island 02912, USA.
Department of Physics, State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
J Chem Phys. 2015 Mar 28;142(12):124309. doi: 10.1063/1.4916122.
We report a photodetachment and high-resolution photoelectron imaging study of cold 2-hydroxyphenoxide anion, o - HO(C6H4)O(-), cooled in a cryogenic ion trap. Photodetachment spectroscopy revealed a dipole-bound state (DBS) of the anion, 25 ± 5 cm(-1), below the detachment threshold of 18 784 ± 5 cm−1 (2.3289 ± 0.0006 eV), i.e., the electron affinity of the 2-hydroxyphenoxy radical o - HO(C6H4)O(⋅). Twenty-two vibrational levels of the DBS are observed as resonances in the photodetachment spectrum. By tuning the detachment laser to these DBS vibrational levels, we obtain 22 high-resolution resonant photoelectron spectra, which are highly non-Franck-Condon due to mode-selective autodetachment and the Δv = - 1 propensity rule. Numerous Franck-Condon inactive vibrational modes are observed in the resonant photoelectron spectra, significantly expanding the vibrational information that is available in traditional high-resolution photoelectron spectroscopy. A total of 15 fundamental vibrational frequencies are obtained for the o - HO(C6H4)O(⋅) radical from both the photodetachment spectrum and the resonant photoelectron spectra, including six symmetry-forbidden out-of-plane modes as a result of resonant enhancement.
我们报道了对在低温离子阱中冷却的冷2-羟基苯氧阴离子o-HO(C6H4)O(-)进行的光剥离和高分辨率光电子成像研究。光剥离光谱揭示了该阴离子的一个偶极束缚态（DBS），其能量为25±5 cm(-1)，低于18784±5 cm−1（2.3289±0.0006 eV）的剥离阈值，即2-羟基苯氧基自由基o-HO(C6H4)O(⋅)的电子亲和能。在光剥离光谱中观察到DBS的22个振动能级作为共振峰。通过将剥离激光调谐到这些DBS振动能级，我们获得了22个高分辨率共振光电子能谱，由于模式选择性自剥离和Δv = -1倾向规则，这些能谱高度不符合弗兰克-康登原理。在共振光电子能谱中观察到许多弗兰克-康登非活性振动模式，显著扩展了传统高分辨率光电子能谱中可用的振动信息。从光剥离光谱和共振光电子能谱中总共获得了o-HO(C6H4)O(⋅)自由基的15个基本振动频率，包括由于共振增强而出现的六个对称性禁阻的面外模式。
