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Raman and photoluminescence studies on lowdimensional PbI2 particles embedded in polymer matrix

N. PREDA1,* , L. MIHUT1, M. BAIBARAC1, I. BALTOG1

Affiliation

  1. National Institute of Materials Physics, Lab. of Optics and Spectroscopy, P. O. Box MG-7, RO-77125, Bucharest, Romania

Abstract

PbI2 crystallite incorporated in optically transparent polyacrylamide and poly (vinyl alcohol) matrix have been studied by Raman scattering, photoluminescence (PL) at low temperature and Scanning Electron Microscopy (SEM). The small particles of PbI2 embedded in different host matrix were prepared by: i) cooling to the room temperature a boiling saturated aqueous PbI2 solution containing polyacrylamide or poly (vinyl alcohol) and ii) by chemical reaction of KI and Pb(NO3)2 in aqueous polyacrylamide solution. In all cases, were identified hexagonal platelets of PbI2 and rods like particles. The rods are featured by a similar Raman spectrum and a specific green emission (cca 550 nm). Modification of the Raman and PL spectra results from a compressing effect produced by the penetration between the PbI2 layers of different molecular species. By compression the hybridized electronic level situated at the top of valence band, formed by the contribution of the 6s and 5p states of Pb2+ and I- ions, undergo a deformation that induces a weakness of the interaction between the lead ion and iodine electron within a layer so that the photoluminescence of intercalated PbI2 acquires the characteristics of Pb2+ emission when it is dissolved in an alkali halide crystal..

Keywords

Lead iodide crystallites, Polyacrylamide, Poly (vinyl alcohol), Raman scattering, Photoluminescence.

Submitted at: Nov. 14, 2006
Accepted at: May 15, 2007

Citation

N. PREDA, L. MIHUT, M. BAIBARAC, I. BALTOG, Raman and photoluminescence studies on lowdimensional PbI2 particles embedded in polymer matrix, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 5, pp. 1358-1361 (2007)