Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Origin of defect-related green emission from ZnO nanoparticles: effect of surface modification | Nanoscale Res Lett 2007 2 297-302 DOI s11671-007-9064-6 NANO EXPRESS Origin of defect-related green emission from ZnO nanoparticles effect of surface modification Yinyan Gong Tamar Andelman Gertrude F. Neumark Stephen O Brien Igor L. Kuskovsky Received 28 February 2007 Accepted 11 May 2007 Published online 12 June 2007 to the authors 2007 Abstract We investigated the optical properties of col-loidal-synthesized ZnO spherical nanoparticles prepared from 1-octadecene OD a mixture of trioctylamine TOA and OD 1 10 and a mixture of trioctylphosphine oxide TOPO and OD 1 12 . It is found that the green photoluminescence PL of samples from the mixture of TOA OD and TOPO OD is largely suppressed compared with that from pure OD. Moreover it is found that all spherical nanoparticles have positive zeta potential and spherical nanoparticles from TOA OD and TOPO OD have a smaller zeta potential than those from OD. A plausible explanation is that oxygen vacancies presumably located near the surface contribute to the green PL and the introduction of TOA and TOPO will reduce the density of oxygen vacancies near the surfaces. Assuming that the green emission arises due to radiative recombination between deep levels formed by oxygen vacancies and free holes we estimate the size of optically active spherical nanoparticles from the spectral energy of the green luminescence. The results are in good agreement with results from TEM. Since this method is independent of the degree of confinement it has a great advantage in providing a simple and practical way to estimate the size of spherical nanoparticles of any size. We would like to point out that this method is only applicable for samples with a small size distribution. Y. Gong El T. Andelman G. F. Neumark S. O Brien Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 USA e-mail yg2002@ I. L. Kuskovsky Department of Physics Queens College of CUNY Flushing NY 11367 USA Keywords
