Rotational analysis and tunnel splittings of the intermolecular vibrations of the phenol–water complex by high resolution UV spectroscopy

Abstract

Highly resolved (Δν<100 MHz) UV-REMPI (ultraviolet-resonantly enhanced multiphoton ionization) spectra of different vibronic bands in the phenol–water complex are presented. The torsional splitting caused by the hindered rotation of the water moiety in the hydrogen-bonded system is investigated. An autocorrelation procedure reveals torsional subbands, a correlation automated rotational fitting (CARF) of the spectra yields the rotational constants: The analyzed vibrations are classified by the rotational constants of the corresponding vibronic band and the symmetry of the torsional state. The transition to the stretching vibration at 156 cm−1 excess energy is shown to consist of two different torsional transitions similar to the electronic origin. The torsional splitting in the origin band is 0.8491(2) cm−1 and that of the stretching vibration is 0.8915(3) cm−1, demonstrating a very small coupling between the stretching and the torsional motion. We assign the 121 cm−1 band as the negative parity component of the transition to the wagging vibration β2 while the band at 125 cm−1 is tentatively assigned as the positive parity component of the same band. The resulting large torsional splitting of −4.596(3) cm−1 points to a strong coupling to the torsional motion. The band at 95 cm−1 has only one torsional parity component within its rotational envelope. The observed large change of its rotational constants does not fit to the pattern of the other vibrations and the band is tentatively assigned as an overtone of the torsional vibration τ with positive parity.

Noncovalent Interactions and Internal Dynamics in Dimethoxymethane–Water

“…When water is linked as a proton acceptor, as in the case of indole-W, [1] phenol-W, [2][3][4] and species Ic (with a N À H···O linkage) of formamide-W, [5] the W subunit is relatively free to rotate with respect to the OM. As a consequence, splittings are observable in the pure rotational spectra, [1,3] from which information on the potential-energy surface is obtained.…”

Structures of hydrogen-bonded clusters of benzyl alcohol with water investigated by infrared-ultraviolet double resonance spectroscopy in supersonic jet

“…[27][28][29][30][31][32][33][34][35][36][37] Among many spectroscopic works, vibrational spectroscopy of the OH stretching vibration is particularly important to analyze their structures, because the OH stretching vibration is a sensitive probe of the hydrogen-bond structure. Vibrational spectroscopy of the OH stretching vibrations for the size-selected clusters has become possible by using IR-UV double resonance spectroscopy.…”

The structure of 4-methylphenol and its water cluster revealed by rotationally resolved UV spectroscopy using a genetic algorithm approach

“…An easy way of finding spectral splittings ͑and thus obtaining information about the required Hamiltonian͒ is to perform an autocorrelation of the spectrum. This method has been shown by Helm et al to be helpful in the analysis of the phenol-water cluster spectrum 31 and later by Remmers et al in the analysis of the tunneling spectrum of the benzoic acid dimer. 32 Nevertheless, if one component of the complete spectrum amounts to more than 50% of the total intensity, the GA is capable of fitting this part of the spectrum, although it might be concealed in the dense spectrum of other component͑s͒ and would therefore be inaccessible to a classical analysis using line-positionassigned fits.…”