Detailed analysis of the vibronic structure of phenetole in its first excited state and ionic ground state

Abstract

The vibronic structure of the first electronically excited state S 1 and ionic ground state D 0 of phenetole has been investigated by means of resonance enhanced multi photon ionization (REMPI) and mass analyzed threshold ionization (MATI) spectroscopy. The vibronic levels were assigned with the aid of quantum chemical calculations at the (TD)DFT level of theory and a multidimensional Franck-Condon approach. The S 1 excitation energy of phenetole has been determined to be 36370 AE 4 cm À1 (4.5093 AE 0.0005 eV). The adiabatic ionization energy was determined to be 65665 AE 7 cm À1 (8.1415 AE 0.0008 eV). The vibronic structure has been analyzed whereby the in-plane bending vibration bend shows high activity in the first excited state but is more pronounced in the ionic ground state. Moreover, a strong Duschinsky rotation effect can be observed for several D 0 S 1 transitions that causes violations of the Áv ¼ 0 propensity rule.

Two-Color Resonant Two-Photon Mass-Analyzed Threshold Ionization of 2,4-Difluoroanisole and the Additivity Relation of Ionization Energy

“…Thus, simple FC overlap approximations based on harmonic vibration are not adequate for estimating the intensities of some vibronic bands. The simulated vibronic spectra of anisole, phenetole, trans -2-fluorostyrene, and p -chloroanisole have been reported in previous studies. ,,, …”

“…The simulated vibronic spectra of anisole, phenetole, trans-2-fluorostyrene, and p-chloroanisole have been reported in previous studies. 32,33,35,36 The 1C-R2PI experiments revealed that the vibronic transitions of 2,4-difluoroanisole may involve ring-substituent and intramolecular through-space substituent−substituent interactions of the two F atoms and the OCH 3 group as well as ring deformation vibrations. Table 1 lists the observed vibronic bands of 2,4-difluoroanisole (Figure 1a).…”

“…These spectra may be used by researchers as a base for improving the simulation of the cation spectra of 2,4difluoroanisole. The MATI spectra of phenetole 33 and o-, m-, and p-fluorophenylacetylene 42 have been successfully simulated using UB3PW91/6311++G(d,p) calculations.…”

“…In 2008, Bloino et al successfully simulated the vibronic spectrum of anisole on the basis of the Franck–Condon (FC) principle by performing DFT calculations using the B3LYP and TD-B3LYP functionals. Helle et al used the PBE0 functional with a triple-ζ basis to obtain accurate multidimensional FC simulation results for analyzing the vibronic and cation spectra of phenetole in detail. We followed a similar procedure and used the FC approximation implemented in the GAUSSIAN 16 program package to simulate the vibronic and cation spectra of 2,4-difluoroanisole by performing DFT calculations using the B3LYP and B3PW91 functionals with the 6-311++G­(d,p) basis set …”

Cation Vibrations of 1-Methylnaphthalene and 2-Methylnaphthalene through Mass-Analyzed Threshold Ionization Spectroscopy

“…In 2008, Bloino et al and Barone et al successfully simulated vibrationally resolved electronic spectra of benzene derivatives by using the Gaussian package. Recently, Helle et al used the quantum chemical approach to obtain reliable results in multidimensional Franck–Condon simulations for detailed analysis of the vibronic and cation spectra of phenetole. We employed the procedure provided by the Gaussian 16 package for spectral simulation, which involves calculations of electronic spectra and frequency calculations for both initial and final states.…”