TY  - JOUR
A1  - Melani, Giacomo
A1  - Nagata, Yuki
A1  - Saalfrank, Peter
T1  - Vibrational energy relaxation of interfacial OH on a water-covered alpha-Al2O3(0001) surface
T2  - Physical chemistry, chemical physics : PCCP ; a journal of European chemical societies
N2  - Vibrational relaxation of adsorbates is a sensitive tool to probe energy transfer at gas/solid and liquid/solid interfaces. The most direct way to study relaxation dynamics uses time-resolved spectroscopy. Here we report on a non-equilibrium ab initio molecular dynamics (NE-AIMD) methodology to model vibrational relaxation of OH vibrations on a hydroxylated, water-covered alpha-Al2O3(0001) surface. In our NE-AIMD approach, after exciting selected O-H bonds their coupling to surface phonons and to the water adlayer is analyzed in detail, by following both the energy flow in time, as well as the time-evolution of Vibrational Density of States (VDOS) curves. The latter are obtained from Time-dependent Correlation Functions (TCFs) and serve as prototypical, generic representatives of time-resolved vibrational spectra. As most important results, (i) we find a few-picosecond lifetime of the excited modes and (ii) identify both hydrogen-bonded aluminols and water molecules in the adsorbed water layer as main dissipative channels, while the direct coupling to Al2O3 surface phonons is of minor importance on the timescales of interest. Our NE-AIMD/TCF methodology is powerful for complex adsorbate systems, in principle even reacting ones, and opens a way towards time-resolved vibrational spectroscopy.
Y1  - 2021
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/63530
SN  - 1463-9076
SN  - 1463-9084
VL  - 23
IS  - 13
SP  - 7714
EP  - 7723
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  -