Vibronic and Cation Spectroscopy of o-chloroanisole and m-chloroanisole
Date Issued
2011
Date
2011
Author(s)
Huang, Hsin-Chang
Abstract
Here We present the resonance enhanced multiphoton ionization (REMPI) , the photoionization efficiency (PIE) curve, and the mass-analyzed threshold ionization (MATI) spectra of o-, and m-chloroanisole. o-chloroanisole is found to have only one stable structure whose excitation and adiabatic ionization energy are 35745 ± 2 and 66982 ± 5 cm-1, respectively. The vibronic features of m-chloroanisole are built on 35822 ± 2 and 35868 ± 2 cm-1 corresponding to the band origins of S1 ← S0 electronic transition (E1’s) for cis and trans rotamers. The adiabatic ionization energies (IEs) for these two species are found to be 67645 ± 5 and 68008 ± 5 cm-1, respectively.
The excitation and ionization energies between 35Cl and 37Cl isotopomers for these two molecules are found to be the same within present detection limit. Moreover, spectral features between isotopomers are almost the same, and their vibrational frequencies only differ by a few wavenumbers, which may results from the little change in system reduced mass and lower degree of Cl atom involed in the acive molecular motions. According to our experimental findings, the isotope effect caused by Cl substituent is negligible for o-, and m-chloroanisole.
Most of the active vibrations of o-, and m-chloroanisole in electronically excited S1 and cationic ground D0 states is assigned as the substituent-active and in-plane ring vibrations. By comparing these data with those of p-chloroanisole and other similar molecular systems, we can learn more about the vicinal substitution effects not only on electronic transition, ionization, but also molecular vibrations resulting from the relative locations of the Cl and OCH3 substituents.
Subjects
o-chloroanisole
m-chloroanisole
vibronic spectroscopy
cation spectroscopy
mass analyzed threshold ionization spectroscopy
Type
thesis
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