Mass-analyzed threshold ionization spectroscopy of the rotamers of p-n-propylphenol cations and configuration effect

Abstract

Two-color resonant two-photon mass-analyzed threshold ionization (MATI) spectroscopy was used to record the vibrationally resolved cation spectra of the selected rotamers of p-n-propylphenol. The adiabatic ionization energies of the trans, gauche-A, and gauche-B rotamers are determined to be 65 283+/-5, 65 385+/-5, and 65 369+/-5 cm(-1), which are less than that of phenol by 3342, 3240, and 3256 cm(-1), respectively. This suggests that the n-propyl substitution causes a greater degree in lowering the energy level in the cationic than the neutral ground state. Analysis on the MATI spectra of the selected rotamers of p-n-propylphenol cation shows that the relative orientation of the p-n-alkyl group has little effect on the in-plane ring vibrations. However, the low-frequency C(3)H(7) bending vibrations appear to be active only for the two gauche forms of the cation.

Site-Specific H/D Exchange of p-Methoxyphenol Studied by Resonant Two-Photon Ionization and Mass-Analyzed Threshold Ionization Spectroscopy

“…It is noted that the bandwidth in Figures c and c is much broader than that in all other MATI spectra shown in the present paper. A similar finding has been observed in the MATI experiments of p -methylphenol and p - n -propylphenol . Since no fragment ions appeared in the mass spectrum, the observed broad band is not caused by dissociation of molecular ions.…”

Mass analyzed threshold ionization spectroscopy of o-fluorophenol and o-methoxyphenol cations and influence of the nature and relative location of substituents

“…In addition to the sharp 0 + , 1 1 , and 1 2 bands, a broad band appears at a frequency greater than 800 cm À1 . A similar finding has been observed in the MATI experiments of p-methylphenol [36] and p-npropylphenol [45]. We have repeated the experiments for a few times to confirm this observation.…”

Rotamers of m-chloroanisole studied by two-color resonant two-photon mass-analyzed threshold ionization spectroscopy

“…Combining supersonic jet-cooled expansion with laser-induced fluorescence (LIF) [9,10], resonance-enhanced multiphoton ionization (REMPI) [9,11,12], hole-burning [10,[13][14][15] spectroscopic techniques, and theoretical calculations, one can confirm the presence of different rotamers in a chemical sample. These methods can provide information about the active vibrations of rotamers in the electronically excited state.…”