AI 中文总结
研究通过多种方法比较α - Al2O3、α - Fe2O3和α - Rh2O3的性质，探讨d轨道半径对载流子 - 声子耦合的影响，发现α - Rh2O3晶格共价性受4d轨道影响，进而影响光生极化子形成的声子模式。
AI 中文摘要
光生极化子是过渡金属氧化物半导体光物理的基础。理解过渡金属氧化物光激发时极化子形成的机制对于实现其在光应用中的潜力至关重要。赤铁矿（α - Fe2O3）形成光激发小极化子，限制了其作为水氧化光催化剂的性能。本文通过共振拉曼光谱、热差光谱以及电子和振动态计算模型，系统比较了赤铁矿与刚玉晶体家族中其他金属氧化物（α - Al2O3、α - Rh2O3）的电子、光学和振动性质，阐明d轨道半径对载流子 - 声子耦合的影响。发现α - Al2O3因无光学吸收，拉曼光谱不随激发变化；α - Fe2O3和α - Rh2O3在吸收起始处声子与光学跃迁有强耦合。通过比较α - Fe2O3和α - Rh2O3的光学极化子性质，确定α - Rh2O3中4d轨道径向扩展增加导致的晶格共价性增加影响了介导光生极化子形成的声子模式。
英文摘要
Photogenerated polarons are fundamental to the photophysics of transition metal oxide semiconductors. It is therefore imperative to understand the mechanisms by which polarons form upon photoexcitation of transition metal oxides to realize their potential in photoapplications. Hematite (α-Fe2O3) is known to form photoexcited small polarons, which limit its performance as a photoelectrocatalyst for water oxidation. Here, we report a systematic comparison of the electronic, optical and vibrational properties of hematite to those other metal oxides in the corundum crystal family that elucidates the impact of d-orbital radius on carrier-phonon coupling. Three corundum metal oxides are analyzed: α-Al2O3 (no d-electrons), α-Fe2O3 (3d), and α-Rh2O3 (4d) with a combined approach of resonance Raman spectroscopy, thermal difference optical spectroscopy, and computational modeling of electronic and vibrational states. We find that the Raman spectrum of α-Al2O3 does not change as the Raman excitation is varied across the visible region, as there is no optical absorption. In contrast, both α-Fe2O3 and α-Rh2O3 exhibit strong coupling of phonons to optical transitions at the onset of absorption, which is evidence of excitation into a polaronic state. Closely comparing the optical polaronic properties of α-Fe2O3 and α-Rh2O3, we establish that increased lattice covalency in α-Rh2O3 arising from the increased radial extension of the 4d orbitals influences which phonon modes mediate photogenerated polaron formation.
Comments28 pages, 9 figures
Journal refJ. Chem. Phys. 2026, 165, 034702
