Proton-transfer spectroscopy beyond the normal-mode scenario
| Autor: | Florian N. Brünig, Paul Hillmann, Won Kyu Kim, Jan O. Daldrop, Roland R. Netz |
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| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 157:174116 |
| ISSN: | 1089-7690 0021-9606 |
| Popis: | A stochastic theory is developed to predict the spectral signature of proton-transfer processes and is applied to infrared spectra computed from ab initio molecular-dynamics simulations of a single [Formula: see text] cation. By constraining the oxygen atoms to a fixed distance, this system serves as a tunable model for general proton-transfer processes with variable barrier height. Three spectral contributions at distinct frequencies are identified and analytically predicted: the quasi-harmonic motion around the most probable configuration, amenable to normal-mode analysis, the contribution due to transfer paths when the proton moves over the barrier, and a shoulder for low frequencies stemming from the stochastic transfer-waiting-time distribution; the latter two contributions are not captured by normal-mode analysis but exclusively reported on the proton-transfer kinetics. In accordance with reaction rate theory, the transfer-waiting-contribution frequency depends inversely exponentially on the barrier height, whereas the transfer-path-contribution frequency is rather insensitive to the barrier height. |
| Databáze: | OpenAIRE |
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