Vibrational phase relaxation of O–H stretch in bulk water: Role of large amplitude angular jumps and negative cross-correlations among the forces on the O–H bond

Vibrational Spectroscopy as a Probe of Structure and Dynamics in Liquid Water

“…47,48 Concomitantly, this delocalization has a pronounced effect on both the steadystate and ultrafast vibrational spectroscopy, causing, for example, the appearance of a collective vibrational peak in the polarized Raman spectrum 48 and the very rapid anisotropy decay (due to vibrational energy transfer) in pump-probe experiments. [49][50][51][52][53][54] In terms of the study of vibrational dynamics, [55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71] these are important and fascinating effects. They are, however, less relevant to the structure and dynamics of liquid water in thermal equilibrium (where all OH stretch vibrations are in their ground states).…”

“…On the other hand, in condensed phases, there is also the possibility of vibrational coupling between OH stretches on different molecules. Our current understanding is that this coupling has a pronounced effect on instantaneous vibrational eigenstates for single excitations, which can extend over ten or more molecules. , Concomitantly, this delocalization has a pronounced effect on both the steady-state and ultrafast vibrational spectroscopy, causing, for example, the appearance of a collective vibrational peak in the polarized Raman spectrum and the very rapid anisotropy decay (due to vibrational energy transfer) in pump−probe experiments. − In terms of the study of vibrational dynamics, − these are important and fascinating effects. They are, however, less relevant to the structure and dynamics of liquid water in thermal equilibrium (where all OH stretch vibrations are in their ground states).…”

Capturing the Ultrafast Vibrational Decoherence of Hydrogen Bonding in Interfacial Water

“…In solar cells, it is interfaced with metals and semiconductors to produce hydrogen gas. , Many of the interesting properties arise from the hydrogen bonding (O–H) network . Thus, understanding the flow and redistribution of vibrational energy through this network is crucial for the control of O–H bond formation and breaking. , A physical quantity that is sensitive to this spread of energy within the O–H network is the total dephasing time, T 2 , which is directly related to the inhomogeneous line shape of the vibrational transition. , Since in the liquid phase water molecules are surrounded by other molecules that exert forces on them, they undergo ultrafast structural fluctuations that randomize the energy over the entire transition spectral line, an inhomogeneous broadening of the spectral line shape hides the dynamic information contained in the inhomogeneous line. , The pure dephasing time, T * 2 (exclusively due to homogeneous broadening), of the O–H stretch vibration in liquid water was measured using the photon-echo technique to be on the order of 90 fs. , This sub-100 fs time-scale for OH dephasing in liquid water was confirmed by several calculations. − …”

Spatio-temporal correlations in aqueous systems: computational studies of static and dynamic heterogeneity by 2D-IR spectroscopy

“…It is broadly acknowledged that anti-correlation existing between forces on the oxygen and hydrogen atoms of -O-H bonds plays an important role in the decay of FFCFs. 24 Bulk water is found to exhibit ultrafast decay in its FFCF, which essentially arises due to large amplitude angular jumps of water molecules and the appearance of a large cross correlation of projected force on the oxygen and hydrogen atoms of the -O-H bonds. We nd such evidence from the corresponding force trajectories (Fig.…”