title: Enhanced resonant raman scattering and electron-phonon coupling from self-assembled secondary ZnO nanoparticles.
abstract: Self-assembled secondary ZnO nanoparticles, recognized with the agglomeration of crystalline subcrystals, are successfully synthesized by a simple sol-gel method. TEM images display that one artificial cluster behaves in a single-crystal-like wurtzite structure because subcrystals coagulate as the same crystal orientation. Moreover, from the resonant Raman scattering, the as-grown sample exhibits phonon red shift; meanwhile, the coupling strength between electron and longitudinal optical phonon, determined by the ratio of second- to first-order Raman scattering cross sections, diminishes compared with the samples after postannealing at 350 and 500 degrees C. The size dependence of electron-phonon coupling is principally as a result of the Fröhlich interaction.
authors.affiliation: Department of Photonics and Institute of Electro-Optical Engineering, National Chiao Tung University, 1001 Tahsueh Road., Hsinchu 30050, Taiwan, Republic of China.
authors.forename: Hsin-Ming
authors.initials: HM
authors.lastname: Cheng
authors.forename: Kuo-Feng
authors.initials: KF
authors.lastname: Lin
authors.forename: Hsu-Cheng
authors.initials: HC
authors.lastname: Hsu
authors.forename: Chih-Jen
authors.initials: CJ
authors.lastname: Lin
authors.forename: Li-Jiaun
authors.initials: LJ
authors.lastname: Lin
authors.forename: Wen-Feng
authors.initials: WF
authors.lastname: Hsieh