对甲氧基苯甲腈的单色共振双光子电离光谱
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摘要
对甲氧基苯甲腈是一种重要的化学化工原料,本文采用超声分子束技术和共振多光子电离方法获得了对甲氧基苯甲腈的单色共振双光子电离光谱,基态S0到电子激发态S1的0←0跃迁被确定为(35549±2)cm~(-1),结合含时密度泛函理论计算结果对观察到的光谱进行了振动模式标识和描述.实验发现呼吸振动模非常易于激活,其基频和二次泛频光谱很强,三次泛频也可明确标识,观察到大量呼吸振动与其他正则模的结合振动,这是对甲氧基苯甲腈不同于常见的多原子分子的一个重要特性.这些结果为研究对甲氧基苯甲腈的里德堡态、动力学和零动能光谱等提供了重要的参考数据.
p-methoxybenzonitrile is an important chemical and industrial material which has been widely used in many fields,such as medicine,chemistry,photoelectron,etc.In this paper,we use the technologies of supersonic molecular beam,resonance enhanced multiphoton ionization and time-of-flight mass spectrometer to obtain the high-resolution one color resonance two-photon ionization spectra of p-methoxybenzonitrile in a vibrational wavenumber range of 0–2400 cm~(-1).In order to analyze the experimental results,the theoretical calculations are performed.The molecular structure,energy,and vibration frequencies at the electronic excited state S1 are computed with time-dependent density functional theory at the level of B3PW91/6-311 g++**.According to the calculated results,the observed bands are assigned by the method of Varsanyi and Szoke.The band origin of the S1← S0 electronic transition of p-methoxybenzonitrile is determined to be(35549 ± 2) cm~(-1).A lot of vibrational bands of the electronic excited state S1 are observed.The results show that the vibrational modes of 9b,6b,15 and 1 are very easy to activate in a wavenumber range of 0–800 cm~(-1).There are also a lot of intense bands in a wavenumber range of 800–1600 cm~(-1).In addition to the fundamental vibrations,many combined vibrations between breathing and other fundamental vibrations are found.Several vibrations in this range are located at OCH3 and CN group.Most of the bands in a range of 1600–2400 cm~(-1)correspond to ones in the range of 800–1600 cm~(-1).Except for the bands appearing at 1664 and 2156 cm~(-1),which are assigned to 15101310andν(CN)(CN stretching) respectively,the remaining bands in the range of 1600–2400 cm~(-1)are assigned as the combined vibrations between the breathing and the corresponding modes in the range of 800–1600 cm~(-1),i.e.,the combined vibrations between the breathing overtone and other fundamental modes.Our theoretical calculations show that except for CN stretching vibration at 2162 cm~(-1),there is no fundamental frequency in a range of 1600–3000 cm~(-1),which is consistent with our experimental result and assignment.The fundamental of the breathing vibration 11 and its second overtone vibration 12 are very strong.The third overtone frequency 13 can be identified unambiguously.This is an important characteristic of p-methoxybenzonitrile,which is different from that of the usual polyatomic molecule.These results provide important reference for future researches on Rydberg states,chemical kinetics and zero kinetic energy spectroscopy of p-methoxybenzonitrile.
p-methoxybenzonitrile is an important chemical and industrial material which has been widely used in many fields,such as medicine,chemistry,photoelectron,etc.In this paper,we use the technologies of supersonic molecular beam,resonance enhanced multiphoton ionization and time-of-flight mass spectrometer to obtain the high-resolution one color resonance two-photon ionization spectra of p-methoxybenzonitrile in a vibrational wavenumber range of 0–2400 cm~(-1).In order to analyze the experimental results,the theoretical calculations are performed.The molecular structure,energy,and vibration frequencies at the electronic excited state S1 are computed with time-dependent density functional theory at the level of B3PW91/6-311 g++**.According to the calculated results,the observed bands are assigned by the method of Varsanyi and Szoke.The band origin of the S1← S0 electronic transition of p-methoxybenzonitrile is determined to be(35549 ± 2) cm~(-1).A lot of vibrational bands of the electronic excited state S1 are observed.The results show that the vibrational modes of 9b,6b,15 and 1 are very easy to activate in a wavenumber range of 0–800 cm~(-1).There are also a lot of intense bands in a wavenumber range of 800–1600 cm~(-1).In addition to the fundamental vibrations,many combined vibrations between breathing and other fundamental vibrations are found.Several vibrations in this range are located at OCH3 and CN group.Most of the bands in a range of 1600–2400 cm~(-1)correspond to ones in the range of 800–1600 cm~(-1).Except for the bands appearing at 1664 and 2156 cm~(-1),which are assigned to 15101310andν(CN)(CN stretching) respectively,the remaining bands in the range of 1600–2400 cm~(-1)are assigned as the combined vibrations between the breathing and the corresponding modes in the range of 800–1600 cm~(-1),i.e.,the combined vibrations between the breathing overtone and other fundamental modes.Our theoretical calculations show that except for CN stretching vibration at 2162 cm~(-1),there is no fundamental frequency in a range of 1600–3000 cm~(-1),which is consistent with our experimental result and assignment.The fundamental of the breathing vibration 11 and its second overtone vibration 12 are very strong.The third overtone frequency 13 can be identified unambiguously.This is an important characteristic of p-methoxybenzonitrile,which is different from that of the usual polyatomic molecule.These results provide important reference for future researches on Rydberg states,chemical kinetics and zero kinetic energy spectroscopy of p-methoxybenzonitrile.
引文
[1]Huang L C L,Lin J L,Tzeng W B 2000 Chem.Phys.261 449
[2]Li C Y,Pradhan M,Tzeng W B 2005 Chem.Phys.Lett.411 506
[3]Huang J G,Li C Y,Tzeng W B 2005 Chem.Phys.Lett.414 276
[4]Li C Y,Su H,Tzeng W B 2005 Chem.Phys.Lett.41099
[5]Lui Y H,Mc Glynn S P 1975 J.Mol.Spectrosc.55 163
[6]Bocharov V N,Bureiko S F,Golubev N S,Shajakhmedov S S 1998 J.Mol.Stuct.444 57
[7]Fleminga G D,Golsioa I,Aracena A,Celis F,Vera L,Koch R,Campos-Vallette M 2008 Spectrchim.Acta A71 1074
[8]Liu H,Li M,Xie X G,Wu C,Deng Y K,Wu C Y,Gong Q H,Liu Y Q 2015 Chin.Phys.Lett.32 063301
[9]Zhang J F,Lu H,Zuo W L,Xu H F,Jin M X,Ding D J 2015 Chin.Phys.B 24 113301
[10]Chen Z,Tong Q N,Zhang C C,Hu Z 2015 Chin.Phys.B 24 043303
[11]Kroto H W,Heath J R,O’Brien S C,Curl R F,Smalley R E 1985 Nature 318 162
[12]Posthumus J 2001 Molecules and Clusters in Intense Laser Fields(New York:Cabridge University Press)pp84–112
[13]Yao G X,Wang X L,Du C M,Li H M,Zhang X Y,Zheng X F,Ji X H,Cui Z F 2006 Acta Phys.Sin.552210(in Chinese)[姚关心,王小丽,杜传梅,李慧敏,张先燚,郑贤锋,季学韩,崔执凤2006物理学报55 2210]
[14]Zhang Q,Li X,Zhao Y,Yang Y G,Li C Y,Jia S T 2016Acta Sin.Quan.Opt.22 115(in Chinese)[张庆,李鑫,赵岩,杨勇刚,李昌勇,贾锁堂2016量子光学学报22 115]
[15]Tzeng W B,Lin J L 1999 J.Phys.Chem.A 103 8612
[16]Wang Y,Yao Z,Feng C L,Liu J H,Ding H B 2012 Acta Phys.Sin.61 013301(in Chinese)[王燕,姚志,冯春雷,刘佳宏,丁洪斌2012物理学报61 013301]
[17]Song K,Hayes J M 1989 J.Mol.Spectrosc.134 82
[18]Frisch M J,Trucks G W,Schlegel H B,Scuseria G E,Robb M A,et al.2009 Gaussian 09(Pittsburgh:Gaussian Inc.)
[19]Li C Y,Lin J L,Tzeng W B 2005 J.Chem.Phys.122044311
[20]Varsanyi G,Szoke S 1969 Vibrational spectra of Benzene Derivatives(New York and London:Academic Press)p129
[21]Varsanyi G 1974 Assignments for Vibrational Spectra of Seven Hundred Benzene Derivatives(New York:Halsred Press)p185
[2]Li C Y,Pradhan M,Tzeng W B 2005 Chem.Phys.Lett.411 506
[3]Huang J G,Li C Y,Tzeng W B 2005 Chem.Phys.Lett.414 276
[4]Li C Y,Su H,Tzeng W B 2005 Chem.Phys.Lett.41099
[5]Lui Y H,Mc Glynn S P 1975 J.Mol.Spectrosc.55 163
[6]Bocharov V N,Bureiko S F,Golubev N S,Shajakhmedov S S 1998 J.Mol.Stuct.444 57
[7]Fleminga G D,Golsioa I,Aracena A,Celis F,Vera L,Koch R,Campos-Vallette M 2008 Spectrchim.Acta A71 1074
[8]Liu H,Li M,Xie X G,Wu C,Deng Y K,Wu C Y,Gong Q H,Liu Y Q 2015 Chin.Phys.Lett.32 063301
[9]Zhang J F,Lu H,Zuo W L,Xu H F,Jin M X,Ding D J 2015 Chin.Phys.B 24 113301
[10]Chen Z,Tong Q N,Zhang C C,Hu Z 2015 Chin.Phys.B 24 043303
[11]Kroto H W,Heath J R,O’Brien S C,Curl R F,Smalley R E 1985 Nature 318 162
[12]Posthumus J 2001 Molecules and Clusters in Intense Laser Fields(New York:Cabridge University Press)pp84–112
[13]Yao G X,Wang X L,Du C M,Li H M,Zhang X Y,Zheng X F,Ji X H,Cui Z F 2006 Acta Phys.Sin.552210(in Chinese)[姚关心,王小丽,杜传梅,李慧敏,张先燚,郑贤锋,季学韩,崔执凤2006物理学报55 2210]
[14]Zhang Q,Li X,Zhao Y,Yang Y G,Li C Y,Jia S T 2016Acta Sin.Quan.Opt.22 115(in Chinese)[张庆,李鑫,赵岩,杨勇刚,李昌勇,贾锁堂2016量子光学学报22 115]
[15]Tzeng W B,Lin J L 1999 J.Phys.Chem.A 103 8612
[16]Wang Y,Yao Z,Feng C L,Liu J H,Ding H B 2012 Acta Phys.Sin.61 013301(in Chinese)[王燕,姚志,冯春雷,刘佳宏,丁洪斌2012物理学报61 013301]
[17]Song K,Hayes J M 1989 J.Mol.Spectrosc.134 82
[18]Frisch M J,Trucks G W,Schlegel H B,Scuseria G E,Robb M A,et al.2009 Gaussian 09(Pittsburgh:Gaussian Inc.)
[19]Li C Y,Lin J L,Tzeng W B 2005 J.Chem.Phys.122044311
[20]Varsanyi G,Szoke S 1969 Vibrational spectra of Benzene Derivatives(New York and London:Academic Press)p129
[21]Varsanyi G 1974 Assignments for Vibrational Spectra of Seven Hundred Benzene Derivatives(New York:Halsred Press)p185