Tanner, AJ;
Wen, B;
Zhang, Y;
Liu, L-M;
Fielding, HH;
Selloni, A;
Thornton, G;
(2021)
Photoexcitation of bulk polarons in rutile TiO₂.
Physical Review B
, 103
(12)
, Article L121402. 10.1103/physrevb.103.l121402.
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Abstract
The excitation of surface-localized polaronic states has recently been discussed as an additional photocatalytic channel to band gap excitation for rutile Ti O 2 . A contribution from photoexcitation of bulk polarons could, in principle, provide a greater contribution because of their higher number and their protection from oxidation. However, determining such a contribution to the photoyield is challenging and has not been achieved thus far. Here we use two photon photoemission spectroscopy measurements to separate bulk and surface polaron photoexcitation. We find that bulk polarons are less bound by 0.2 eV compared with polarons at the surface, consistent with our results of hybrid density functional theory calculations. Because the excited state is also shifted to higher energy, bulk polarons have the same photoexcitation resonance energy as at the surface (3.6 eV) with a threshold at 3.1 eV. This is degenerate with the band gap, suggesting that bulk polarons could also provide an additional contribution to the photoyield.
| Type: | Article |
|---|---|
| Title: | Photoexcitation of bulk polarons in rutile TiO₂ |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1103/physrevb.103.l121402 |
| Publisher version: | https://doi.org/10.1103/physrevb.103.l121402 |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Density of states, First-principles calculations, Photoinduced effect, Polarons, Energy materials, Density functional theory, Two-photon photoelectron spectroscopy |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10125454 |
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