Gu Quanli, Trindle Carl O, Knee J L
R. J. Reynolds Tobacco Company, Winston Salem, North Carolina 27105, United States.
J Phys Chem A. 2014 Jul 10;118(27):4982-7. doi: 10.1021/jp5045578. Epub 2014 Jun 27.
Resonance-enhanced multiphoton ionization spectroscopy of supersonically cooled gas-phase 9-hydroxy-9-fluorene carboxylic acid (9HFCA) is reported for its first electronic excited state, S1. The UV-UV hole-burning experiment identifies a single conformer in the molecular beam, stabilized by an intramolecular hydrogen bond. For this Cs symmetric conformer, two low frequencies in the S1 spectrum are assigned: an in-plane rocking mode of the carboxylic acid side chain lies at 58 cm(-1), and an in-plane fluorene bending mode appears at 183 cm(-1). The corresponding mode frequencies in the cation, 58 and 196 cm(-1), are measured by zero electron kinetic energy (ZEKE) spectroscopy upon pumping the S1 vibronic states. The adiabatic ionization potential is measured to be 64 923 ± 5 cm(-1). In addition, a feature established by ZEKE spectroscopy upon pumping the hot band is found at 67 cm(-1). This is assigned as a hot band of the HO-C9-COOH rocking mode in the neutral ground state.
报道了对超声冷却气相9-羟基-9-芴羧酸（9HFCA）的第一电子激发态S1进行共振增强多光子电离光谱研究。紫外-紫外空穴烧蚀实验确定了分子束中的单一构象异构体，它通过分子内氢键得以稳定。对于这种具有Cs对称性的构象异构体，在S1光谱中确定了两个低频：羧酸侧链的面内摇摆模式位于58 cm⁻¹，芴的面内弯曲模式出现在183 cm⁻¹。在泵浦S1振动态时，通过零电子动能（ZEKE）光谱测量阳离子中相应的模式频率为58和196 cm⁻¹。测得绝热电离势为64923±5 cm⁻¹。此外，在泵浦热谱带时通过ZEKE光谱确定的一个特征出现在67 cm⁻¹处。这被指定为中性基态中HO-C9-COOH摇摆模式的热谱带。
