邻羟基苯腈的双色共振增强多光子电离光谱及Franck-Condon模拟  

Two-color resonance enhanced multiphoton ionization spectroscopy of o-hydroxybenzonitrile and Franck-Condon simulation

作　　者：李娜[1] 李淑贤 王林 王慧慧[1,2] 杨勇刚 赵建明[1,2] 李昌勇 Li Na;Li Shu-Xian;Wang Lin;Wang Hui-Hui;Yang Yong-Gang;Zhao Jian-Ming;Li Chang-Yong(State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Laser Spectroscopy,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学激光光谱研究所量子光学与光量子器件国家重点实验室,太原030006 [2]山西大学极端光学协同创新中心,太原030006

出　　处：《物理学报》2022年第2期52-59,共8页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2017YFA0304203);国家自然科学基金重点项目(批准号:61835007);国家自然科学基金(批准号:11904215,61575115);长江学者和创新团队发展计划(批准号:IRT17R70);高等学校学科创新引智基地(111计划)(批准号:D18001);山西省“1331工程”重点学科建设计划资助的课题。

摘　　要：在自制直线式飞行时间质谱仪上进行了双色共振增强双光子电离实验,获得了振动分辨的邻羟基苯腈的共振增强多光子电离(resonance enhanced multiphoton ionization,REMPI)光谱,结合高精度密度泛函理论计算和Franck-Condon光谱模拟,详细分析了光谱特征,发现了大量基频、泛频和组合振动,并进行了光谱归属.大部分苯环的基频振动归属为环在平面内的畸变或平面内的摇摆,这与分子激发过程中苯环的扩张有关.理论和实验结果都表明,REMPI光谱的低频段信号强,背景低,谱带少,分辨率好.随着振动频率的增加,信号向相反的方向变化.这是由于低频段光谱主要来自于低频的基频振动、少量泛频的贡献.随着振动频率增加,泛频和各种模的组合振动逐渐增多,导致了高频区谱带稠密,分辨率变差.高阶振动和多模的组合振动通常有较低的Franck-Condon因子,因此信号随频率增大逐渐变弱,信噪比变差.The cyano group is a typical electron-withdrawing group,which has aroused the interest of relevant researchers.Many papers reported the dispersed fluorescence spectra of o-hydroxybenzonitrile,its dimers,and complexes with small molecules,aiming to study the intermolecule hydrogen bond and the vibration features of the electronic ground state.There are also reports on using fluorescence excitation spectra to study excited state vibrations,but no report on the systematical analyzing of the vibration features of excited state spectra.Compared with fluorescence spectroscopy,resonance enhanced multiphoton ionization(REMPI) spectroscopy detects ions to obtain excited state energy level data,which has mass-resolution capability,and eliminates the interference of impurities with different charge-to-mass ratios.The strong electron-withdrawing ability of cyano group results in higher ionization energy for molecules containing cyano groups.Many REMPI experiments on benzonitrile derivatives require two-color lasers.In this paper,two-color resonance enhanced two-photon ionization experiment is performed by using a home-made linear time-of-flight mass spectrometer,and the vibration-resolved REMPI spectrum of o-hydroxybenzonitrile is obtained for the first time.Combining the highprecision density functional theory calculations with the Franck-Condon spectral simulations,the spectral characteristics are analyzed in detail,and a large number of fundamental,overtone and combined vibrations are found.The spectral assignment is carried out as accurately as possible.Most of the fundamental vibrations located at ring are assigned to the in-plane distortion or swing of the ring,which is related to the expansion of the ring during the molecular excitation.Theoretical and experimental results show that the low-frequency signal of REMPI spectrum is strong,the background is low,the band is less,and the resolution is good.As the vibration frequency increases,the signal changes in the worse direction.This is because the low-frequency spectru

关 键 词：邻羟基苯腈 双色共振增强多光子电离 光谱模拟 振动光谱 

分 类 号：TQ246.7[化学工程—有机化工] O657.3[理学—分析化学]