|Title||Direct evidence of angular jumps during water reorientation through two-dimensional infrared anisotropy|
|Publication Type||Journal Article|
|Year of Publication||2010|
|Authors||Stirnemann G, Laage D|
|Journal||J. Phys. Chem. Lett.|
Water reorientation was recently suggested via simulations to proceed through large angular jumps, but direct experimental evidence has so far remained elusive. Here we show that both infrared pump-probe and photon echo spectroscopies can provide such evidence through the measurement of the two-dimensional anisotropy decay. We calculate these two-dimensional anisotropies from simulations and show they can be interpreted as a vibrational frequency-dependent resolved orientation time-correlation function. We develop a frequency-dependent extended jump model to predict the nature of the angular jump signature in these anisotropies. This model provides a rigorous and unambiguous connection between ultrafast infrared experimental results and the presence of angular jumps in bulk water, and calls for new experiments.