Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles

Lijie Wang, Tsz Him Chow, Malte Oppermann, Jianfang Wang, Majed Chergui

Research output: Contribution to journalArticlepeer-review


We report on deep-to-near-UV transient absorption spectra of core-shell Au/SiO2Au/SiO2 and Au/TiO2Au/TiO2 nanoparticles (NPs) excited at the surface plasmon resonance of the Au core, and of UV-excited bare anatase TiO2TiO2 NPs. The bleaching of the first excitonic transition of anatase TiO2TiO2 at ∼3.8 eV∼3.8 eV 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 TiO2TiO2 NPs, two-photon excitation does not occur up to the highest used fluences (1.34 mJ/cm21.34 mJ/cm2), it takes place in the TiO2TiO2 shell at moderate fluences (0.18 mJ/cm20.18 mJ/cm2) in Au/TiO2Au/TiO2 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 ∼108–109∼108–109. Remarkably, we observe that the bleach of the 3.8 eV band of TiO2TiO2 lives significantly longer than in bare TiO2TiO2, suggesting that the excess electrons/holes in the conduction/valence band are stored longer in this material.
Original languageEnglish (US)
Pages (from-to)1303-1313
Number of pages11
JournalPhotonics Research
Issue number7
StatePublished - Jun 28 2023

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics


Dive into the research topics of 'Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles'. Together they form a unique fingerprint.

Cite this