Combining frequency and time domain vibrational sum-frequency generation (vSFG) measurements can reveal information that is not readily accessible in one approach alone. In particular, the ultrafast free induction decay (FID-vSFG) has the added advantage that it can reveal the relative phases of the oscillators contributing to the response. FID-vSFG measurements at the water/CaF2 interface are consistent with two distinct populations of interfacial hydrogen bonded species that are oriented oppositely, one more strongly bonded than the other, and dephase on sub 100 fs timescales. Similar experiments at water-Al2O3 interfaces suggest that there are two kinds of free OH oscillators; non-hydrogen bonded AlOH species as well as incompletely hydrogen bonded water.

Capturing the ultrafast vibrational decoherence of water at mineral interfaces

253rd National Meeting (2017)

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