Abstract
Abstract Two-color resonant two-photon mass-analyzed threshold ionization spectroscopy was applied to study the vibrationally resolved cation spectra of the of 1-cyanonaphthalene; structural isomers of o-fluorophenylacetylene, m-fluorophenylacetylene, p-fluorophenylacetylene, and p-fluorophenylacetylene water complex; selected rotamers of 2,4-difluorophenol, selected rotamers and isotopologus of 4-chloro-3-fluorophenol and 4-chloro-3-fluorophenol water complexes. The S1 ← S0 electronic transition energy and the adiabatic ionization energies of these molecular species has been precisely measured along with this we performed ab initio and density functional theory calculations to predict the molecular structure, vibration, and electronic transition and ionization energies to strengthen our experimental findings. Moreover we compare these experimental finding with respective similar molecular species. The present 2,4-difluorophenol experimental results show that only cis form involved in the photo-excitation and ionization processes, due to presences of intramolecular hydrogen bonding. While in case of 4-chloro-3-fluorophenol, there are two stable rotamers and isotopologus (35Cl and 37Cl) coexisting in the sample. Analysis on the MATI spectra shows that most of the active cation vibrations of these molecular species result from in-plane ring motions. Moreover, different orientations of the two OH groups have little effect on these vibrations. Comparing the data of cis-2,4-difluorophenol and 4-chloro-3-fluorophenol with those of phenol, cis-2-fluorophenol, 3-fluorophenol, 4-fluorophenol and 4-chlorophenol one can learn that there may have an additivity rule associated with the energy shift resulting from the additional fluorine and chlorine substitution. Frequency shifts in these molecules somewhat depends on the nature, vibrational pattern, location and relative orientation of the substitutents.