R2PI detection and spectroscopy of van der Waals complexes of 4-fluorostyrene with rare gases

Dissymmetry effects on the laser spectroscopy of supersonically expanded rare gas/chiral arene heteroclusters

The R2PI-TOF spectra of supersonically expanded rare gas/chiral arene heteroclusters have been rationalized in terms of the distortion of the pi-electron density reflecting the different dipole and quadrupole momenta induced in the rare gas atoms by interaction with the opposite pi-faces of the chiral arene itself.

Fully dimensional ab initio description of the structure and energetics of azabenzene-argon complexes

The structure and energetics of van der Waals complexes of argon with azabenzenes: pyridine, pyrazine, pyrimidine, pyridazine, s-triazine, and s-tetrazine are studied using the second-order Moller-Plesset perturbation theory combined with well-balanced basis sets. The full optimization of the cluster structures and computation of the inter- and intramolecular vibrational frequencies is performed by eliminating the basis set superposition error. The argon equilibrium coordinates are calculated with the accuracy comparable to that reached by standard methods of the structure determination from the spectral data. A simple rule to predict the position of argon with respect to the geometric center of the azabenzene ring is found. The calculated harmonic frequencies of the intermolecular vibrational modes are scaled by the factor of 0.85 to eliminate systematic errors coming from the neglect of anharmonic effects. The scaled frequencies agree with the experimental ones to about 1 cm(-1), except for pyrimidine-argon and tetrazine-argon for which empirical fundamental frequency estimates are problematic. A simple relation connecting the intermolecular bending frequencies and the monomer quadrupole tensor is found. The perturbation of the monomer properties caused by complexation is analyzed. The modification of the monomer structure by the interaction with argon and its influence on the binding energy appears to be negligible in all complexes studied. However, this interaction affects appreciably the intramolecular modes and causes their frequency shifts. As a consequence, the dissociation energy of the complexes increases by about 5 cm(-1).

Characteristics and relaxation dynamics of van der Waals complexes between p-difluorobenzene and Ne

Characteristics of the single and double Ne van der Waals complexes of p-difluorobenzene (pDFB) have been explored with ultraviolet fluorescence excitation and dispersed fluorescence spectroscopy. Eight S(1)-S(0) fluorescence excitation bands involving six ring modes of pDFB-Ne and two bands of pDFB-Ne(2) have been identified. Band assignments are confirmed by dispersed fluorescence from the pumped band. Shifts of the complex bands from the analogous monomer bands are generally 4 cm(-1) to the red for pDFB-Ne and 8 cm(-1) for pDFB-Ne(2). None of the observed ring modes is significantly perturbed by complexation in either the S(1) or S(0) states. The pDFB-Ne S(1) van der Waals binding energy D(0')</=120 cm(-1) is inferred from fluorescence band assignments with D(0')-D(0")=4 cm(-1). Vibrational predissociation of pDFB-Ne to produce the S(1) monomer is observed after pumping several levels, but the dissociation process is generally slow compared to fluorescence decay of the complex. Dissociation of the double complex pDFB-Ne(2) occurs from one level to produce S(1) pDFB-Ne in its zero point level. Comparisons are made with the relaxation dynamics of the S(1) complexes pDFB-Ar and pDFB-N(2).