CAJ | 학술논문

间甲基苯甲醚分子有顺式和反式两个转动异构体.利用单光共振双光子电离技术和质量分辨阈值电离技术,研究了间甲基苯甲醚分子顺反异构体的基态到第一电子激发态(S1←S0)的跃迁和阈值电离.得到顺式、反式间甲基苯甲醚分子S1态的激发能(E1)分别为(36049±2)和(36117±2) cm-1,绝热电离能(Ip)分别为(64859±5)和(65110±5) cm-1.结合从头算法和密度泛函理论的量子化学计算,解释了顺式、反式间甲基苯甲醚分子E1和Ip存在差异的原因,并且对S1态和离子基态D0态出现的谱峰进行了标识.间甲基苯甲醚分子顺反异构体在S1态和D0态的活性振动主要是甲基转动、面内环的运动和与取代基相关的弯曲振动.间甲基苯甲醚分子的S1态振动光谱、D0态离子光谱以及理论计算均表明这两个转动异构体在D0态的几何构型与S1态的中性几何构型相比有较大改变,取代基与取代基、取代基与苯环间的相互作用强度高低次序为：S0<S1<D0.
간갑기분갑미분자유순식화반식량개전동이구체.이용단광공진쌍광자전리기술화질량분변역치전리기술,연구료간갑기분갑미분자순반이구체적기태도제일전자격발태(S1←S0)적약천화역치전리.득도순식、반식간갑기분갑미분자S1태적격발능(E1)분별위(36049±2)화(36117±2) cm-1,절열전리능(Ip)분별위(64859±5)화(65110±5) cm-1.결합종두산법화밀도범함이론적양자화학계산,해석료순식、반식간갑기분갑미분자E1화Ip존재차이적원인,병차대S1태화리자기태D0태출현적보봉진행료표식.간갑기분갑미분자순반이구체재S1태화D0태적활성진동주요시갑기전동、면내배적운동화여취대기상관적만곡진동.간갑기분갑미분자적S1태진동광보、D0태리자광보이급이론계산균표명저량개전동이구체재D0태적궤하구형여S1태적중성궤하구형상비유교대개변,취대기여취대기、취대기여분배간적상호작용강도고저차서위：S0<S1<D0.
The S1←S0 electronic transition and threshold ionization of the cis and trans rotamers of m-methylanisole were investigated by using one-color resonant two-photon ionization and mass-analyzed threshold ionization techniques. The first electronic excitation energies (E1) of the cis and trans rotamers were determined to be (36049 ± 2) and (36117 ± 2) cm-1, while the adiabatic ionization energies (Ip) were (64859 ± 5) and (65110 ± 5) cm- 1, respectively. The results of ab initio and density functional theory calculations provide a satisfactory interpretation for our experimental findings concerning the difference in the transitional energies of the cis and trans rotamers and assist in assigning the vibronic and cation spectra obtained in the present study. The observed active vibrations of both rotamers in the S1 and D0 states primarily consist of methyl torsion, in-plane ring deformation, and substituent-sensitive bending modes. Both experimental and theoretical results show that, for both cis and trans isomers, the geometry of the cation in the D0 state is somewhat different from that of the neutral species in the S1 state. In addition, the strengths of both the through-space substituent-substituent and substituent-ring interactions were found to fol ow the order:S0<S1<D0.