Vibronic and cation spectroscopy of selected rotamers of 4-chloro-3-fluorophenol

Abstract

We applied the two-colour resonant two-photon ionisation and mass-analysed threshold ionisation techniques to record the vibrationally resolved spectra of the selected rotamers and 35 Cl and 37 Cl isotopologues of 4-chloro-3-fluorophenol in the electronically excited S 1 and cationic ground D 0 states. The band origins of the S 1 ← S 0 electronic transition and the adiabatic ionisation energies of the cis and trans rotamers of 4-chloro-3-fluorophenol are determined to be 35,233 ± 2 and 35,405 ± 2 cm −1 , and 69,334 ± 5 and 69,460 ± 5 cm −1 , respectively. The electronic transition energies and general spectral features of the two isotopologues are nearly identical. Most of the observed active vibrations result from the inplane ring deformation and substituent-sensitive motions. The experimental data show that the frequency difference in the observed active vibrations of the rotamers and isotopologues depends on the nature, vibrational pattern, location, and relative orientation of the substituents.

Tuning the Stereoselectivity and Solvation Selectivity at Interfacial and Bulk Environments by Changing Solvent Polarity: Isomerization of Glyoxal in Different Solvent Environments

“…At ambient temperature, conformational isomers are mixed together since the rotational barrier is often comparable to the thermal energy. The ultrafast cooling that is achieved during supersonic expansion was investigated as a potential option for conformer separation in molecular beam experiments. − Cooling of macroscopic condensed phases may be an option to investigate; however, the resulting relative population of conformers upon cooling is likely to be biased by the initial population at higher temperature. These difficulties and the lack of a clear methodology to achieve conformer separation reveal a deficiency in the understanding at the molecular level of the driving mechanisms for conformational interconversion, especially in the condensed phase.…”