Vibrational energy relaxation pathways of water

Vibrational energy relaxation (VR) of the OH stretch v(OH) and bend delta(H2O) in water is studied by the mid-IR pump with anti-Stokes Raman probe technique. The broad I OH band in water consists of two inhomogeneously broadened subbands. VR in the larger red-shifted subband v(OH)(R),withT(1) = 0.55 ps, is shown to occur by the mechanism v(OH) --> delta(H2O) (1/3) and v(OH) --> ground state (2/3). VR in the smaller longer-lived blue-shifted subband v(OH)(B), with T-1 = 0.75 ps, occurs by the mechanism v(OH) --> ground state. The bending fundamental delta(H2O) decays directly to the ground state with T-1 = 1.4 ps. (C) 2003 Elsevier B.V. All rights reserved.