Ultrafast dynamics of transient bleaching of surface modified cadmium sulphide nano-particles in Nafion films

Abstract

Ultrafast dynamics of transient photobleaching and recovery of cadmium sulphide (CdS) nanoparticles in Nafion films before and after treatment with excess cadmium ions have been studied upon excitation at 400 nm with a femtosecond laser system. Both samples gave transient bleaching in less than 1 ps and a multi-exponential recovery in the wavelength region between ca. 410 and 500 nm. Cd2+ treatment of the nanoparticles resulted in several dramatic changes to the fluorescence and transient bleaching spectra from the films: (1) A new fluorescence band at higher energy appeared in addition to an increase in the 'defect' fluorescence band at longer wavelengths. (2) A remarkable increase in the e..