我們利用共振雙光子游離與質量解析臨界游離光譜術來紀錄4-氯-3-氟苯胺(4C3FA)及4-氯-3-氟苯甲醚(4C3FAN)的第一電子激發態暨離子態光譜，用以探討分子的特性。以目前的儀器解析度極限，35Cl與37Cl具有相同的第一電子躍遷能(E1)和絕熱游離能(IE)，4C3FA分別為33 242及63 868 cm-1，順-4-氯-3-氟苯甲醚為35 295及67 279 cm-1，而反-4-氯-3-氟苯甲醚則為35 412及67 548 cm-1。依據光譜分析結果顯示大多數之譜峰為苯環平面運動及取代基之彎曲運動。
將4C3FA的數據與4-氯苯胺、3 -氟苯胺和苯胺比較，我們發現在第一電子躍遷能和絕熱游離能存在添加規則(additivity rule)，這意味著取代基氯、氟、胺基的作用力是微弱的。除此之外，我們也利用從頭計算法(ab initio)及密度泛函理論與實驗結果對照，提供合理的解釋數據。
而本實驗所測得4C3FA與4C3FAN的第一電子激發態振動光譜和離子態光譜可以用作指紋分子鑑定。

We applied the resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of 4-chloro-3-fluoroaniline and 4-chloro-3-fluoroanisole to investigate their molecular properties. The excitation energy of the S1 ← S0 transition (E1) and the adiabatic ionization energy (IE) of 4-chloro-3-fluoroaniline are found to be 33 242 and 63 868 cm-1, respectively. Comparing these data with those of 4-chloroaniline, 3-fluoroaniline, and aniline, we find an additivity rule associated with the E1 and IE. This implies that the interaction among the Cl, F, and NH2 substituents is weak. The vibronic featues of 4-chloro-3-fluoroanisole are found to build on 35 295 and 35 412 cm-1 corresponding to the band origins of S1 ← S0 electronic transition (E1) for cis and trans rotamers. The adiabatic ionization energies (IEs) for these two species are found to be 67 279 and 67 548 cm-1, respectively. These newly recorded vibronic and cation spectra can be used as fingerprints for molecular identification.

[1] T. Ebata, A. Fujii, Naohiko, Mikami, Vibrational spectroscopy of small-sized hydrogen-bonded clusters and their ions, Int. Rev. Phys. Chem. 17 (1998) 331-361.
[2] T. Watanabe, T. Ebata, S. Tanabe, N. Mikami, Size-selected vibrational spectra of phenol-(H2O)(n) (n=1-4) clusters observed by IR-UV double resonance and stimulated Raman-UV double resonance spectroscopies, J. Chem. Phys. 105 (1996) 408-419.
[3] G. Brehm, G. Sauer, N. Fritz, S. Schneider, S. Zaitsev, Correlation spectroscopy based on non-linear response of silver colloids (including SEHRS), J. Mol. Struct. 735 (2005) 85-102.
[4] G.N. Patwari, S. Doraiswamy, S. Wategaonkar, Spectroscopy and IVR in the S-1 state of jet-cooled p-alkoxyphenols, J. Phys. Chem. A 104 (2000) 8466-8474.
[5] T. Ichimura, T. Suzuki, Photophysics and photochemical dynamics of methylanisole molecules in a supersonic jet, J. Photochem. Photobiol. C: Photochem. Rev.1 (2000) 79-107.
[6] A. Nakajima, M. Hirano, R. Hasumi, K. Kaya, H. Watanabe, C.C. Carter, J.M. Williamson, T.A. Miller, High-resolution laser-induced fluorescence spectra of 7-azaindole-water complexes and 7-azaindole dimer, J. Phys. Chem. A 101 (1997) 392-398.
[7] C. Nordling, E. Sokolowski, K. Siegbahn, Precision method for obtaining absolute values of atomic binding energies, Phys. Rev. 105 (1957) 1676-1677.
[8] S. Hagström, C. Nordling, K. Siegbahn, Electron spectroscopy for chemical analysis, Phys. Lett. 9 (1964) 235-236.
[9] D.W. Turner, M.I. Al Joboury, Determination of ionization potentials by photoelectron energy measurement, J. Chem. Phys. 37 (1962) 3007.
[10] K. Watanabe, Photoionization and total absorption cross section of gases .1. ionization potentials of several molecules - cross sections of nh3 and no, J. Chem. Phys. 22 (1954) 1564-1570.
[11] G.C. King, A.J. Yencha, M.C.A. Lopes, Threshold photoelectron spectroscopy using synchrotron radiation, J. Electron Spectrosc. Relat. Phenom. 114 (2001) 33-40.
[12] T. Baer, Y. Li, Threshold photoelectron spectroscopy with velocity focusing: an ideal match for coincidence studies, Int. J. Mass Spectrom. 219 (2002) 381-389.
[13] K. Muller-Dethlefs, M. Sander, E.W. Schlag, 2-color photoionization resonance spectroscopy of no - complete separation of rotational levels of no+ at the ionization threshold, Chem. Phys. Lett. 112 (1984) 291-294.
[14] L.A. Chewter, M. Sander, K. Muller-Dethlefs, E.W. Schlag, High-resolution zero kinetic-energy photoelectron-spectroscopy of benzene and determination of the ionization-potential, J. Chem. Phys. 86 (1987) 4737-4744.
[15] E.W. Schlag, ZEKE Spectroscopy, Cambridge University Press, Cambridge, (1998).
[16] L. Zhu, P.M. Johnson, Resonance-enhanced multiphoton ionization-photoelectron spectra of co2 .1. photoabsorption above the ionization-potential, J. Chem. Phys. 94 (1991) 7596-7601.
[17] X. Song, M. Yang, E.R. Davidson, J.P. Reilly, Zero kinetic-energy photoelectron-spectra of jet-cooled aniline, J. Chem. Phys. 99 (1993) 3224-3233.
[18] X.Q. Tan, D.W. Pratt, High-resolution electronic spectroscopy of p-toluidine - a precessing rotor model for g(12) molecules, J. Chem. Phys. 100 (1994) 7061-7067.
[19] S. Wateganonkar, S. Doraiswamy, Jet spectroscopy of p-methoxyaniline and intramolecular vibrational relaxation dynamics in the p-alkoxyaniline series, J. Chem. Phys. 106 (1997) 4894-4901.
[20] J.L. Lin, W.B. Tzeng, Mass analyzed threshold ionization of the Cl-35 and Cl-37 isotopomers of p-chloroaniline, J. Chem. Phys. 113 (2000) 4109-4115.
[21] J.L. Lin, S.C. Yang, Y.C. Yu, W.B. Tzeng, Mass analyzed threshold ionization of p-bromoaniline: heavy atom effects on electronic transition, ionization, and molecular vibration, Chem. Phys. Lett. 356 (2002) 267-276.
[22] J.L. Lin, W.B. Tzeng, Ionization energy of o-fluoroaniline and vibrational levels of o-fluoroaniline cation determined by mass-analyzed threshold ionization spectroscopy, Phys. Chem. Chem. Phys. 2 (2000) 3759-3763.
[23] J.L. Lin, K.C. Lin, W.B. Tzeng, Species-selected mass-analyzed threshold ionization spectra of m-fluoroaniline cation, Appl. Spectrosc. 55 (2001) 120-124.
[24] W.B. Tzeng, J.L. Lin, Ionization energy of p-fluoroaniline and vibrational levels of p-fluoroaniline cation determined by mass-analyzed threshold ionization spectroscopy, J. Phys. Chem. A 103 (1999) 8612-8619.
[25] W.C. Huang, W.B. Tzeng, Cation spectroscopy of 3,4-difluoroaniline by two-color resonant two-photon mass-analyzed threshold ionization, J. Mol. Spectrosc. 266 (2011) 52-56.
[26] K.W. Lo, W.B. Tzeng, 3-Chloro-4-fluoroaniline studied by resonant two-photon ionization and mass-analyzed threshold ionization spectroscopy, J. Mol. Spectrosc. 288 (2013) 1-6.
[27] J. Lin, W.B. Tzeng, Two-color resonant two-photon mass analyzed threshold ionization spectroscopy of aromatic molecules, Trends in Appl. Spectrosc. 5 (2004) 71-82.
[28] K.S. Shiung, D. Yu, S.Y. Tzeng, W.B. Tzeng, Cation spectroscopy of o-fluoroanisole and p-fluoroanisole by two-color resonant two-photon mass-analyzed threshold ionization, Chem. Phys. Lett. 524 (2012) 38-41
[29] K.S. Shiung, D. Yu, H.C. Huang, W.B. Tzeng, Rotamers of m-fluoroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy, J. Mol. Spectrosc. 274 (2012) 43-47.
[30] H.C. Huanga, B.Y. Jin, W.B. Tzeng, Two-color resonant two-photon ionization and mass-analyzed threshold ionization spectroscopy of o-chloroanisole, J. Photochem. Photobiol. A：Chem. 243 (2012) 73-79.
[31] H.C. Huang, K.S. Shiung, B.Y. Jin, W.B. Tzeng, Rotamers of m-chloroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy, Chem. Phys. 425 (2013) 114-120.
[32] D. Yu, C.W. Dong, M. Cheng, L. Hu, Y.K. Du, Q.H. Zhu, C.H. Zhang, Resonance-enhanced multiphoton ionization (REMPI) spectroscopy of the Cl-35 and Cl-37 isotopomers of p-chloroanisole, J. Mol. Spectrosc. 265 (2011) 86-91.
[33] Y. Xu, S.Y. Tzeng, B. Zhang, W.B. Tzeng, Rotamers of 3,4-difluoroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy, Spec. Acta. Spectrochim. Acta A 102 (2013) 365-370.
[34] D. Yu, C.W, Dong, L.J. Zhang, M. Cheng, L.L. Hu, Y.K. Du, Q.H. Zhu, C.H. Zhang, Resonant two-photon ionization spectroscopy of the Cl-35 and Cl-37 isotopomers of cis and trans 3-chloro-4-fluoroanisole, J. Mol. Struct. 1000 (2011) 92-98.
[35] L.J. Zhang, D. Yu, C.W. Dong, M. Cheng, L.L. Hu, Z.M. Zhou, Y.K. Du, Q.H. Zhu, C.H. Zhang, Rotamers and isotopomers of 3-chloro-5-fluoroanisole studied by resonant two-photon ionization spectroscopy and theoretical calculations, 104 (2013) 235-242.
[36] P.M. Johnson, C.E. Otis, Molecular multi-photon spectroscopy with ionization detection, Annu. Rev. Phys. Chem. 32 (1981) 139-157.
[37] U. Boesl, H.J. Neusser, E.W. Schlag, Multi-photon ionization in the mass-spectrometry of polyatomic-molecules - cross-sections, Chem. Phys. 55 (1981) 193-204.
[38] H. Ikoma, K. Takazawa, Y. Emura, S. Ikera, H. Abe, H. Hayashi, M. Fujii, Internal rotation of methyl group in o- and m-toluidine cations as studied by pulsed field ionization zero kinetic energy spectroscopy, J. Chem. Phys. 105 (1996) 10201-10209.
[39] F. Merk, Molecules in high Rydberg states, Annu. Rev. Phys. Chem. 48 (1997) 675-709.
[40] K. Muller-Dethlefs, E.W. Schlag, Chemical applications of zero kinetic energy (ZEKE) photoelectron spectroscopy, Angew. Chem. Int. Ed. Engl. 37 (1998) 1346-1374.
[41] M.G.H. Boogaarts, I. Holleman, R.T. Jongma, D.H. Parker, G. Meijer, U. Even, High Rydberg states of DABCO: Spectroscopy, ionization potential, and comparison with mass analyzed threshold ionization, J. Chem. Phys. 104 (1996) 4357-4364.
[42] W.A. Chupka, Factors affecting lifetimes and resolution of rydberg states observed in zero-electron-kinetic-energy spectroscopy, J. Chem. Phys. 98 (1993) 4520-4530.
[43] M.D. Fayer, ELEMENT OF QUANTUM MECHANICS. Oxford (2001) 133.
[44] F. Schlicht, M. Entfellner, U. Boesl, Anion ZEKE-Spectroscopy of the weakly bound iodine water complex, J. Phys. Chem. A 114 (2010) 11125-11132.
[45] S.Y. Ketkov, H.L. Selzle, F.G.N. Cloke, G.V. Markin, Y.A. Shevelev, G.A. Domrachev, E.W. Schlag, Zero kinetic energy spectroscopy: mass-analyzed threshold ionization spectra of chromium sandwich complexes with alkylbenzenes, (eta(6)-RPh)(2)Cr (R = Me, Et, i-Pr, t-Bu), J. Phys. Chem. A 114 (2010) 11298-11303.
[46] C. Bassmann, U. Boesl, D. Yang, G. Drechsler, E.W. Schlag, Mass selective anion-ZEKE spectroscopy of the iodine-water cluster, Int. J. Mass Spectrom. 159 (1996) 153-167.
[47] G. Scoles, D. Bassi, U. Buck, D.C. Laine, Oxford University Press. Oxford, 1988.
[48] W.C. Wiley, I.H. Mclaren, Time-of-flight mass spectrometer with improved resolution, Rev. Sci. Instrum. 26 (1955) 1150-1157.
[49] J.H. Moore, C.C. Davis, M.A. Coplan, S.C. Greer, Building scientific apparatus, University of Maryland, College Park, 2002
[50] W. Baumgart and J. Schmid, Space-charge saturation in channel electron multipliers, J. Phys. D : Appl. Phys. 5 (1972) 1769-&.
[51] J.L. Wiza, Microchannel plate detectors, Nuclear Instruments and Methods. 162 (1979) 587-601.
[52] User’s manual (Spectra-Physics LAB-150)
[53] User’s manual(Lambda Physik Scanmate)
[54] Exciton laser dyes 30 years of excellence and more brilliant than ever.
[55] J.L. Lin, W.B. Tzeng, Mass analyzed threshold ionization of deuterium substituted isotopomers of aniline and p-fluoroaniline: isotope effect and site-specific electronic transition, J. Chem. Phys. 115 (2001) 743-751.
[56] Gaussian 09, Revision A.02, M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, J.A. Montgomery, Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M. Challacombe, P.M. W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, and J.A. Pople, Gaussian, Inc., Wallingford CT, 2009.
[57] M.J. Fresch et al., Gaussian 03, Revision C.02, Gaussian, Inc., Wallingford CT, 2004.
[58] S.F. Boys, Electronic wave functions .1. a general method of calculation for the stationary states of any molecular system, Proc. R. Soc. London Ser. A 200 (1950) 542-544.
[59] G. Varsanyi, Assignments of Vibrational Spectra of Seven Hundred Benzene Derivatives, Wiley, New York, 1974.
[60] V. Shivatar, W.B. Tzeng, Vibronic and spectroscopy of selected rotamers of 4- Chloro-3-fluorophenol, Mol. Phys. (2014)
[61] E.B. Wilson, Calculation of vibrational isotope effect in polyatomic molecules by a perturbation method, Physical Review. 45 (1934) 427-427.
[62] M. Pradhan, C. Li, J.L. Lin, W.B. Tzeng, Mass analyzed threshold ionization spectroscopy of anisole cation and the OCH3 substitution effect, Chem. Phys. Lett. 407 (2005) 100-104.
[63] W.C. Huang, W.L. Yeh, W.B. Tzeng, Vibronic and cation spectroscopy of m-chloroaniline, J. Mol. Spectrosc. 269 (2011) 248-253.
[64] J.L. Lin, K.C. Lin, W.B. Tzeng, Mass-analyzed threshold ionization spectroscopy of o-, m-, and p-methylaniline cations: vicinal substitution effects on electronic transition, ionization, and molecular vibration, J. Phys. Chem. A 106 (2002) 6462-6468.
[65] W.C. Huang, P.S. Huang, C.H. Hu, W.B. Tzeng, Vibronic and cation spectroscopy of 2,4-difluoroaniline, Spectrochim. Acta A 93 (2012) 176-179.
[66] C. Qin, S.Y. Tzeng, B. Zhang, W.B. Tzeng, Active vibrations of indene cation studied by mass-analyzed threshold ionization spectroscopy, J. Photohchem. Photobiol. A 220 (2011) 139-144.
[67] S.Y. Tzeng, J.Y. Wu, S. Zhang, Resonant two-photon mass-analyzed threshold ionization spectroscopy of 1-fluoronaphthalene and 2-fluoronaphthalene, J. Mol. Spectrosc. 281 (2012) 40-46.