DIRECT OBSERVATION OF ULTRAFAST ELECTRON INJECTION FROM COUMARIN-343 TO TIO2 NANOPARTICLES BY FEMTOSECOND INFRARED-SPECTROSCOPY

Citation
Hn. Ghosh et al., DIRECT OBSERVATION OF ULTRAFAST ELECTRON INJECTION FROM COUMARIN-343 TO TIO2 NANOPARTICLES BY FEMTOSECOND INFRARED-SPECTROSCOPY, JOURNAL OF PHYSICAL CHEMISTRY B, 102(34), 1998, pp. 6482-6486
Citations number
52
Categorie Soggetti
Chemistry Physical
Journal title
JOURNAL OF PHYSICAL CHEMISTRY B
ISSN journal
15206106 → ACNP
Volume
102
Issue
34
Year of publication
1998
Pages
6482 - 6486
Database
ISI
SICI code
1089-5647(1998)102:34<6482:DOOUEI>2.0.ZU;2-8
Abstract
Transient infrared (IR) absorption of injected electrons in colloidal TiO2 nanoparticles in the 1900-2000 cm(-1) region are measured by femt osecond IR spectroscopy. The direct detection of electrons in the nano particles with subpicosecond time resolution provides a new approach t o study ultrafast interfacial electron transfer between semiconductor nanoparticles and molecular adsorbates. The dynamics of electron injec tion from sensitizers to nanoparticles and the subsequent back-transfe r and relaxation dynamics of the injected electrons correspond to the rise and decay of the transient IR signal of injected electrons. Using this technique, the injection time for coumarin 343 sensitized TiO2 n anoparticles in D2O is determined to be 125 +/- 25 fs. The subsequent decay dynamics of the injected electrons in nanoparticles are found to be different from conduction band electrons in a bulk TiO2 crystal.