Effect of Structural Fluctuations on Elastic Lifetimes of Adsorbate States: Isonicotinic Acid on Rutile(110)

We sample ab initio molecular dynamics trajectories to address the impact of structural fluctuations on elastic lifetimes of adsorbate states at room temperature focusing on heterogeneous charge injection from isonicotinic acid as a key anchoring unit in dye-sensitized energy devices. Complementing related theoretical studies, we employ a Green's function technique based on density functional theory to account for a fully semi-infinite substrate of rutile TiO₂(110). We address the effect of a core-excitation enabling direct comparison with soft X-ray experiments. We find that room temperature fluctuations drastically improve the agreement with experimental lifetime measurements while the core-hole plays an important role shifting the spectra and reducing the electron vibrational coupling of the adsorbate states. Ultimately, the emerging resonance spectra highlight the role of the continuum of acceptor states in temperature broadened Voigt-type profiles.