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Proceedings Paper

Spectroscopic analysis of single wide-gap semiconductor nanoparticle (Conference Presentation)
Author(s): Yuika Saito; Takahiro Kondo; Mahiro Hanazawa; Kenta Hirose; Ryosuke Kojima; Takeru Yumoto

Paper Abstract

Wide-band gap semiconductor nanoparticles has been the focus of interest recently, due to their validity for energy creations, decomposition of harmful substances, boosting useful chemical reactions etc. In this work, we will evaluate optical characteristics of a single semiconductor nanoparticle via broadband-UV Rayleigh scattering spectroscopy and photoluminescence (PL) spectroscopy. Rayleigh scattering spectroscopy reveal the bandgap energies while PL spectroscopy provide the information on exciton generation efficiencies as well as existence of surface defects. In our microscopy setup, a broadband white light source (LDLS) was collimated and obliquely illuminated on the sample to realize dark-field illumination to distinguish the position of individual particles in the microscopic image. Scattering from a single nanocrystal was collected by an reflection-type objective lens (NA0.5) and introduced to a spectrometer and detected by an EMCCD camera. The spectrometer was designed specifically for UV-DUV broadband spectroscopy and imaging. For photoluminescence (PL) measurements, we introduce 320 nm (CW) laser for excitation. The sample is enclosed in a temperature-controlled cell ranging from room temperature to 77K. We especially focus on titanium dioxide (TiO2), a typical photocatalyst, and tangusten trioxide (WO3) which is one of the candidate for decomposition of water into oxygen and hydrogen by a visible or longer wavelength light. The band structure of nano-particles is changed when the size is smaller than several tens of nanometers, due to crystallinity and quantum size effects. PL of single zinc oxide (ZnO) nanoparticles were also measured together with the temperature effects. The spectra obtained from a single nanoparticle is different from aggregates both for exciton PL and defects PL.

Paper Details

Date Published: 9 September 2019
Proc. SPIE 11086, UV and Higher Energy Photonics: From Materials to Applications 2019, 110860V (9 September 2019); doi: 10.1117/12.2527971
Show Author Affiliations
Yuika Saito, Gakushuin Univ. (Japan)
Takahiro Kondo, Gakushuin Univ. (Japan)
Mahiro Hanazawa, Gakushuin Univ. (Japan)
Kenta Hirose, Gakushuin Univ. (Japan)
Ryosuke Kojima, Gakushuin Univ. (Japan)
Takeru Yumoto, Gakushuin Univ. (Japan)

Published in SPIE Proceedings Vol. 11086:
UV and Higher Energy Photonics: From Materials to Applications 2019
Gilles Lérondel; Yong-Hoon Cho; Atsushi Taguchi; Satoshi Kawata, Editor(s)

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