A detailed experimental study of the water trimer is reported. A vibration-rotation-tunneling band of the perdeuterated cluster has been measured near 89.6 wave numbers by tunable far infrared laser absorption spectroscopy. The data indicate a chiral six-membered ring structure with rapid quantum tunneling occurring between the enantiomers. The observed vibration involves torsional motion of the water subunits about each hydrogen bond axis. It is speculated that larger water clusters would also exhibit transient chirality and that similar effects may be found in liquid water.

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Electron states of benzene-Br2 donor-acceptor complex: HeI photoelectron spectroscopy and ab initio molecular orbital study Measurement of the intermolecular vibration-rotation tunneling spectrum of the ammonia dimer by tunable far infrared laser spectroscopy J. Chem. Phys. 94, 4776 (1991); 10.1063/1.460562Tunable farinfrared laser spectroscopy of hydrogen bonds: The K a =0(u)→1(g) rotation-tunneling spectrum of the HCl dimerThe first accurate measurement of an intermolecular vibration of the water dimer is reported. Five vibration-rotation-tunneling (VRT) bands of the perdeuterated isotope, located near 84 cm -I, have been assigned to the AilE IBI tunneling components of the Ka = 0-0 and Ka = 1 -0 subbands. The vibration involves large amplitude motion of the hydrogen bond acceptor and is assigned as the Vs acceptor wag. The spectra indicate strong coupling of both the donor-acceptor interconversion and donor tunneling motions to the excited vibrational coordinate. This measurement provides a benchmark for future efforts toward the determination of an accurate potential energy surface for the water dimer.

Seven rovibrational transitions of the (01(1)0) <-- (00(0)0) fundamental bending band of C3 have been measured with high precision with the use of a tunable far-infrared laser spectrometer. The C3 molecules were produced by laser vaporization of a graphite rod and cooled in a supersonic expansion. The astrophysically important nu 2 fundamental frequency is determined to be 63.416529(40) cm-1. These measurements provide the basis for studies of C3 in the interstellar medium with far-infrared astronomy.

The vibrational population dynamics of HgI fragments in ethanol solution, resulting from the 320 nm photolysis of HgI 2 , are examined both experimentally and by a simulation. The experiments reveal an HgI population distribution which rapidly relaxes toward equilibrium. At the earliest times, the HgI exhibits vibrational coherent wave-packet motion that dephases with a time constant of ca. 1 ps. These data are used to gain insight into the character of the solvated potential energy curves. The population relaxation was adequately reproduced by master equations which were formulated to incorporate the HgI anharmonicity and a solvent frequency dependent friction. This treatment characterizes the spontaneous vibrational relaxation timescale for the nЉϭ1→0 transition to be ca. 3 ps, and is used to identify the relaxation rate constants for all other HgI level pairs. The simulations estimate that the initial excess energy of HgI is centered at nЉХ10 which corresponds to a total excess energy of ca. 1050 cm Ϫ1 .