Department of Chemistry, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
J Phys Chem B. 2013 Dec 12;117(49):15512-8. doi: 10.1021/jp4053743. Epub 2013 Aug 20.
We present two-dimensional (2D) infrared (IR) spectra of isotope diluted ice in its low density amorphous form. Amorphous ice, which is structurally more similar to liquid water than to crystalline ice, provides higher resolution spectra of the hydrogen bond potentials because all motion is frozen. In the case of OD vibration of HOD in H2O, diagonal and off-diagonal (intermode) anharmonicity as well as the relaxation rate of the first excited state increase with hydrogen bond strength in a consistent way. For the OH vibration of HOD in D2O, additional more specific couplings need to be taken into account to explain the 2D IR response, that is, a Fermi resonance with the HOD bend vibration and couplings to phonon modes that lead to quantum beating. The lifetime of the fist excited state, 240 fs, is the shortest ever reported for any phase of isotope diluted water.
我们展示了处于低密度非晶态的同位素稀释冰的二维（2D）红外（IR）光谱。非晶冰在结构上比结晶冰更类似于液态水，因为所有的运动都被冻结，所以它提供了氢键势能的更高分辨率光谱。在 H2O 中 HOD 的 OD 振动的情况下，对角和非对角（模间）非谐性以及第一激发态的弛豫速率以一致的方式随氢键强度增加。对于 D2O 中的 HOD 的 OH 振动，需要考虑额外的更具体的耦合来解释 2D IR 响应，即与 HOD 弯曲振动的费米共振以及导致量子拍频的声子模式耦合。第一激发态的寿命为 240 fs，是任何同位素稀释水相态中报告的最短寿命。
