Experimental and Theoretical Study on p-Chlorofluorobenzene in the S0, S1 and D 0 States

The geometric structures and vibration frequencies of \begin{document}$ para $\end{document} -chlorofluorobenzene ( \begin{document}$ p $\end{document} -ClFPh) in the first excited state of neutral and ground state of cation were investigated by resonance-enhanced multiphoton ionization and slow electron velocity-map imaging. The infrared spectrum of S \begin{document}$ _0 $\end{document} state and absorption spectrum for S \begin{document}$ _1 $\end{document} \begin{document}$ \leftarrow $\end{document} S \begin{document}$ _0 $\end{document} transition in \begin{document}$ p $\end{document} -ClFPh were also recorded. Based on the one-color resonant two-photon ionization spectrum and two-color resonant two-photon ionization spectrum, we obtained the adiabatic excited-state energy of \begin{document}$ p $\end{document} -ClFPh as 36302 \begin{document}$ \pm $\end{document} 4 cm \begin{document}$ ^{-1} $\end{document} . In the two-color resonant two-photon ionization slow electron velocity-map imagin spectra, the accurate adiabatic ionization potential of \begin{document}$ p $\end{document} -ClFPh was extrapolated as 72937 \begin{document}$ \pm $\end{document} 8 cm \begin{document}$ ^{-1} $\end{document} via threshold ionization measurement. In addition, Franck-Condon simulation was performed to help us confidently ascertain the main vibrational modes in the S \begin{document}$ _1 $\end{document} and D \begin{document}$ _0 $\end{document} states. Furthermore, the mixing of vibrational modes between S \begin{document}$ _0 $\end{document} \begin{document}$ \rightarrow $\end{document} S \begin{document}$ _1 $\end{document} and S \begin{document}$ _1 $\end{document} \begin{document}$ \rightarrow $\end{document} D \begin{document}$ _0 $\end{document} has been analyzed.