Giant two-photon absorption of anatase TiO_(2) in Au/TiO_(2) core-shell nanoparticles  

作　　者：LIJIE WANG TSZ HIM CHOW MALTE OPPERMANN JIANFANG WANG MAJED CHERGUI 

机构地区：[1]Laboratory of Ultrafast Spectroscopy,ISIC and Lausanne Centre for Ultrafast Science(LACUS),École Polytechnique Fédérale de Lausanne(EPFL),CH-1015 Lausanne,Switzerland [2]Department of Physics,The Chinese University of Hong Kong,Shatin,Hong Kong SAR,China [3]Division of Physical Science and Engineering,King Abdullah University of Science and Technology(KAUST),Thuwal,Kingdom of Saudi Arabia [4]Chemistry Department,University of Basel,4001 Basel,Switzerland

出　　处：《Photonics Research》2023年第7期1303-1313,共11页光子学研究（英文版）

基　　金：Horizon 2020 European Research Council Advanced Grant (DYNAMOX);Schweizerischer Nationalfonds zur Forderung der Wissenschaftlichen Forschung (NCCR:MUST);China Scholarship Council。

摘　　要：We report on deep-to-near-UV transient absorption spectra of core-shell Au∕SiO_(2) and Au∕TiO_(2) nanoparticles(NPs) excited at the surface plasmon resonance of the Au core, and of UV-excited bare anatase TiO_(2) NPs. The bleaching of the first excitonic transition of anatase TiO_(2) at ~3.8 e V is a signature of the presence of electrons/holes in the conduction band(CB)/valence band(VB) of the material. We find that while in bare anatase TiO_(2) NPs, two-photon excitation does not occur up to the highest used fluences(1.34 mJ∕cm^(2)), it takes place in the TiO_(2) shell at moderate fluences(0.18 mJ∕cm^(2)) in Au∕TiO_(2) core-shell NPs, as a result of an enhancement due to the plasmon resonance. We estimate the enhancement factor to be of the order of ~10~8–10~9. Remarkably, we observe that the bleach of the 3.8 eV band of TiO_(2) lives significantly longer than in bare TiO_(2), suggesting that the excess electrons/holes in the conduction/valence band are stored longer in this material.

关 键 词：material ABSORPTION EXCITED 

分 类 号：TB383.1[一般工业技术—材料科学与工程]