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

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

doi:10.1364/PRJ.487784

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

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

Physical Sciences and Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

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 language	English (US)
Pages (from-to)	1303-1313
Number of pages	11
Journal	Photonics Research
Volume	11
Issue number	7
DOIs	https://doi.org/10.1364/PRJ.487784
State	Published - Jun 28 2023

Bibliographical note

KAUST Repository Item: Exported on 2023-09-06
Acknowledgements: Horizon 2020 European Research Council Advanced Grant (DYNAMOX); Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (NCCR:MUST); China Scholarship Council. The authors thank Dr. L. Mewes, Dr. M. Puppin, and B. Bauer for helpful discussions. L.W. acknowledges support from the China Scholarship Council (CSC).

ASJC Scopus subject areas

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

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10.1364/PRJ.487784

https://repository.kaust.edu.sa/bitstream/10754/694127/1/Wang%20et%20al-Phot.%20Res.%20AcceptedManuscript.pdf

Cite this

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title = "Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles",

abstract = "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.",

author = "Lijie Wang and Chow, {Tsz Him} and Malte Oppermann and Jianfang Wang and Majed Chergui",

note = "KAUST Repository Item: Exported on 2023-09-06 Acknowledgements: Horizon 2020 European Research Council Advanced Grant (DYNAMOX); Schweizerischer Nationalfonds zur F{\"o}rderung der Wissenschaftlichen Forschung (NCCR:MUST); China Scholarship Council. The authors thank Dr. L. Mewes, Dr. M. Puppin, and B. Bauer for helpful discussions. L.W. acknowledges support from the China Scholarship Council (CSC).",

year = "2023",

month = jun,

day = "28",

doi = "10.1364/PRJ.487784",

language = "English (US)",

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journal = "Photonics Research",

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T1 - Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles

AU - Wang, Lijie

AU - Chow, Tsz Him

AU - Oppermann, Malte

AU - Wang, Jianfang

AU - Chergui, Majed

N1 - KAUST Repository Item: Exported on 2023-09-06 Acknowledgements: Horizon 2020 European Research Council Advanced Grant (DYNAMOX); Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (NCCR:MUST); China Scholarship Council. The authors thank Dr. L. Mewes, Dr. M. Puppin, and B. Bauer for helpful discussions. L.W. acknowledges support from the China Scholarship Council (CSC).

PY - 2023/6/28

Y1 - 2023/6/28

N2 - 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.

AB - 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.

UR - http://hdl.handle.net/10754/694127

UR - https://opg.optica.org/abstract.cfm?URI=prj-11-7-1303

U2 - 10.1364/PRJ.487784

DO - 10.1364/PRJ.487784

M3 - Article

SN - 2327-9125

VL - 11

SP - 1303

EP - 1313

JO - Photonics Research

JF - Photonics Research

IS - 7

ER -

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

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