Frontispiz: Observation of the Low‐Frequency Spectrum of the Water Trimer as a Sensitive Test of the Water‐Trimer Potential and the Dipole‐Moment Surface

Abstract

Wassercluster Im Forschungsartikel auf S. 11496 berichten M. Havenith et al. das erste vollständige Spektrum des Wassertrimers im Frequenzbereich von 70 bis 620 cm−1. Quantenchemische Rechnungen ermöglichten die Zuordnung der experimentell beobachteten Banden.

Tunneling splittings in the vibrationally excited states of water trimer

“…A dramatic increase of bifurcation splittings in water clusters has recently been observed in experiments. 9,29,30 The TM model, as formulated using instanton theory, 21 is described in Section 2. We also derive the energy shifts symbolically in terms of TM elements for the six mechanisms.…”

“…The pseudorotations in water trimers form a group that is a direct product of 3 cyclic oxygen permutations, G 3 , and inversion, and is isomorphic to C 3h and forms a subgroup of G 48 . The dynamics of flips has thoroughly been studied using reduced-dimensionality models, [60][61][62][63][64] PIMD, 43,44 Monte Carlo methods 9,41,42 and instanton theory. 21,24 TM for the flips is a 6 Â 6 matrix.…”

“…[2][3][4] These rearrangements produce splittings in rovibrational spectra that can be measured using high-resolution far-infrared spectroscopies. 2,[5][6][7][8][9] Tunneling splittings, which vary over many orders of magnitude, are thus a sensitive probe of intermolecular water interactions at far-from-equilibrium geometries. They were first measured for the dimer 10 and trimer 11,12 and, subsequently, for other water clusters up to the decamer.…”

“…7,[13][14][15][16][17][18] Computational modeling of vibrational spectra provides a means to interpret the measurements [19][20][21] and assists in spectral assignments. 8,9 The water trimer is the smallest cyclic water cluster. It displays rich hydrogen bond dynamics of the flips of free hydrogens and bifurcations, in which a hydrogen bond that forms the ring is broken and reformed with the previously free hydrogen.…”

“…5,12,20,26,27 Partially deuterated trimers have also been studied 11 and produce qualitatively different TS patterns. 28 Recently, a drastic increase in TS due to bifurcations in vibrationally excited states was observed in water dimer 8,29 (40Â), trimer 9,29 (400Â) and pentamer 30…”