Journal of Chemical Physics, Vol.113, No.19, 8531-8540, 2000
A theoretical and experimental study of the ethyl-p-aminobenzoate (H2O)(n) (n=1-4) complexes
Weakly bound hydrogen bonded ethyl-p-aminobenzoate/water complexes, referred to henceforth both as EAB/(H2O)(n) (n=1-4) or by their stoichiometry 1:n, have been investigated with a combined approach of mass and light detector laser spectroscopic techniques and ab initio calculations. The experimental studies follow explorations with laser induced fluorescence (LIF), and include one-color resonant enhanced multiphoton ionization (REMPI), two-color REMPI (R2PI), pressure dependent R2PI and hole burning (HB) spectroscopies. Calculations were conducted at the B3LYP/6-31+G(*) level and for the 1:1 complex led to the existence of six stable isomers, identified as the experimental origin bands at +4, +6, +13, +89, +96, and +108 cm(-1) above the bare EAB 0(0)(0) transition. It has been shown that three of these bands originate in the EAB trans conformer, while the other three derive from the EAB gauche conformer. None of the experimental methods used lead us to observe the EAB(H2O)(2) complex spectrum and the inspection of the EAB(H2O)(3) REMPI and R2PI spectra has been shown to be a fragmentation from the EAB(H2O)(4) complex. The structures and identification of the set of isomers are reported and a comparison with the results on the family complexes methyl-p-aminobenzoate/water is discussed.