Flickering dipoles in the gas phase: structures, internal dynamics, and dipole moments of β-naphthol-H2O in its ground and excited electronic states

Adam J Fleisher; Justin W Young; David W Pratt; Alessandro Cembran; Jiali Gao

doi:10.1063/1.3562373

Flickering dipoles in the gas phase: structures, internal dynamics, and dipole moments of β-naphthol-H2O in its ground and excited electronic states

J Chem Phys. 2011 Mar 21;134(11):114304. doi: 10.1063/1.3562373.

Authors

Adam J Fleisher¹, Justin W Young, David W Pratt, Alessandro Cembran, Jiali Gao

Affiliation

¹ Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.

PMID: 21428616
DOI: 10.1063/1.3562373

Abstract

Described here are the rotationally resolved S(1)-S(0) electronic spectra of the acid-base complex cis-β-naphthol-H(2)O in the gas phase, both in the presence and absence of an applied electric field. The data show that the complex has a trans-linear O-H⋅⋅⋅O hydrogen bond configuration involving the -OH group of cis-β-naphthol and the oxygen lone pairs of the attached water molecule in both electronic states. The measured permanent electric dipole moments of the complex are 4.00 and 4.66 D in the S(0) and S(1) states, respectively. These reveal a small amount of photoinduced charge transfer between solute and solvent, as supported by density functional theory calculations and an energy decomposition analysis. The water molecule also was found to tunnel through a barrier to internal motion nearly equal in energy to kT at room temperature. The resulting large angular jumps in solvent orientation produce "flickering dipoles" that are recognized as being important to the dynamics of bulk water.