Issue 37, 2022

State-resolved infrared spectrum of the protonated water dimer: revisiting the characteristic proton transfer doublet peak

Abstract

The infrared (IR) spectra of protonated water clusters encode precise information on the dynamics and structure of the hydrated proton. However, the strong anharmonic coupling and quantum effects of these elusive species remain puzzling up to the present day. Here, we report unequivocal evidence that the interplay between the proton transfer and the water wagging motions in the protonated water dimer (Zundel ion) giving rise to the characteristic doublet peak is both more complex and more sensitive to subtle energetic changes than previously thought. In particular, hitherto overlooked low-intensity satellite peaks in the experimental spectrum are now unveiled and mechanistically assigned. Our findings rely on the comparison of IR spectra obtained using two highly accurate potential energy surfaces in conjunction with highly accurate state-resolved quantum simulations. We demonstrate that these high-accuracy simulations are important for providing definite assignments of the complex IR signals of fluxional molecules.

Graphical abstract: State-resolved infrared spectrum of the protonated water dimer: revisiting the characteristic proton transfer doublet peak

Supplementary files

Article information

Article type
Edge Article
Submitted
07 Jun 2022
Accepted
26 Aug 2022
First published
30 Aug 2022
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2022,13, 11119-11125

State-resolved infrared spectrum of the protonated water dimer: revisiting the characteristic proton transfer doublet peak

H. R. Larsson, M. Schröder, R. Beckmann, F. Brieuc, C. Schran, D. Marx and O. Vendrell, Chem. Sci., 2022, 13, 11119 DOI: 10.1039/D2SC03189B

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