Characterization of the (D2O)2 hydrogen-bond-acceptor antisymmetric stretch by IR cavity ringdown laser absorption spectroscopy

The IR-CRLAS technique has been used to measure the mid-infrared O-D stretching spectrum of the fully deuterated gas-phase water dimer for the first time. The instrumentally limited resolution of 1 GHz resolves the acceptor tunneling splittings and the rotational line manifolds. The analysis of these splittings exploits the local nature of the excitation and yields a description of the acceptor tunneling motion that supports previous experimental and theoretical results.