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Title: Probing the Electronic Structure and Band Gap Evolution of Titanium Oxide Clusters (TiO2)n- (n=1-10) Using Photoelectron Spectroscopy

Abstract

TiO2 is a wide-band gap semiconductor and it is an important material for photocatalysis. Here we report an experimental investigation of the electronic structure of (TiO2)n clusters and how their band gap evolves as a function of size using anion photoelectron spectroscopy (PES). PES spectra of (TiO2)n– clusters for n = 1–10 have been obtained at 193 (6.424 eV) and 157 nm (7.866 eV). The high photon energy at 157 nm allows the band gap of the TiO2 clusters to be clearly revealed up to n = 10. The band gap is observed to be strongly size-dependent for n < 7, but it rapidly approaches the bulk limit at n = 7 and remains constant up to n = 10. All PES features are observed to be very broad, suggesting large geometry changes between the anions and the neutral clusters due to the localized nature of the extra electron in the anions. The measured electron affinities and the energy gaps are compared with available theoretical calculations. The extra electron in the (TiO2)n– clusters for n > 1 appears to be localized in a tricoodinated Ti atom, creating a single Ti3+ site and making these clusters ideal molecular models for mechanisticmore » understanding of TiO2 surface defects and photocatalytic properties.« less

Authors:
;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
918463
Report Number(s):
PNNL-SA-53623
Journal ID: ISSN 0002-7863; JACSAT; 20901; KC0301020; TRN: US0805829
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the American Chemical Society, 129(10):3022-3026; Journal Volume: 129; Journal Issue: 10
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANIONS; DEFECTS; ELECTRONIC STRUCTURE; ELECTRONS; GEOMETRY; MOLECULAR MODELS; PHOTOCATALYSIS; PHOTOELECTRON SPECTROSCOPY; PHOTONS; SPECTRA; TITANIUM OXIDES; Environmental Molecular Sciences Laboratory

Citation Formats

Zhai, Hua-jin, and Wang, Lai S. Probing the Electronic Structure and Band Gap Evolution of Titanium Oxide Clusters (TiO2)n- (n=1-10) Using Photoelectron Spectroscopy. United States: N. p., 2007. Web. doi:10.1021/ja068601z.
Zhai, Hua-jin, & Wang, Lai S. Probing the Electronic Structure and Band Gap Evolution of Titanium Oxide Clusters (TiO2)n- (n=1-10) Using Photoelectron Spectroscopy. United States. doi:10.1021/ja068601z.
Zhai, Hua-jin, and Wang, Lai S. Wed . "Probing the Electronic Structure and Band Gap Evolution of Titanium Oxide Clusters (TiO2)n- (n=1-10) Using Photoelectron Spectroscopy". United States. doi:10.1021/ja068601z.
@article{osti_918463,
title = {Probing the Electronic Structure and Band Gap Evolution of Titanium Oxide Clusters (TiO2)n- (n=1-10) Using Photoelectron Spectroscopy},
author = {Zhai, Hua-jin and Wang, Lai S.},
abstractNote = {TiO2 is a wide-band gap semiconductor and it is an important material for photocatalysis. Here we report an experimental investigation of the electronic structure of (TiO2)n clusters and how their band gap evolves as a function of size using anion photoelectron spectroscopy (PES). PES spectra of (TiO2)n– clusters for n = 1–10 have been obtained at 193 (6.424 eV) and 157 nm (7.866 eV). The high photon energy at 157 nm allows the band gap of the TiO2 clusters to be clearly revealed up to n = 10. The band gap is observed to be strongly size-dependent for n < 7, but it rapidly approaches the bulk limit at n = 7 and remains constant up to n = 10. All PES features are observed to be very broad, suggesting large geometry changes between the anions and the neutral clusters due to the localized nature of the extra electron in the anions. The measured electron affinities and the energy gaps are compared with available theoretical calculations. The extra electron in the (TiO2)n– clusters for n > 1 appears to be localized in a tricoodinated Ti atom, creating a single Ti3+ site and making these clusters ideal molecular models for mechanistic understanding of TiO2 surface defects and photocatalytic properties.},
doi = {10.1021/ja068601z},
journal = {Journal of the American Chemical Society, 129(10):3022-3026},
number = 10,
volume = 129,
place = {United States},
year = {Wed Mar 14 00:00:00 EDT 2007},
month = {Wed Mar 14 00:00:00 EDT 2007}
}