ULTRAFAST DYNAMICS AND NONLINEAR OPTICAL PROPERTIES OF GRAPHENE OXIDES AND NOBLE METAL NANOPARTICLES

Abstract

BY EMPLOYING SEVERAL ULTRAFAST LASER SPECTROSCOPIC TECHNIQUES, SOME INTRIGUING OPTICAL PROPERTIES OF GRAPHENE OXIDES (GO) AND GOLD NANOPARTICLES (AU NPS) HAVE BEEN EXPLORED IN THIS THESIS, INCLUDING NONLINEAR OPTICAL PROPERTIES SUCH AS NONLINEAR ABSORPTION, TWO-PHOTON PHOTOLUMINESCENCE (TPPL) AS WELL AS THE ELECTRONIC RELAXATION DYNAMICS. GOLD NANORODS (AU NRS) AND COUPLED AU NPS ARE KNOWN TO DISPLAY STRONG TPPL. TO FIGURE OUT THE UNDERLYING MECHANISMS, WE DEVELOPED AND PREFORMED TWO-PULSE EMISSION MODULATION AND PUMP-PROBE MEASUREMENTS TO INVESTIGATE THEIR EXCITATION DYNAMICS. OUR RESULTS CLARIFIED THE TPPL EXCITATION NATURE OF AU NPS AND ITS ASSOCIATED QUENCHING MECHANISMS OF AU NRS IN DIFFERENT ORGANIC SOLVENTS COMPARED TO WATER. GO NANOSTRUCTURES WERE ALSO SYSTEMATICALLY STUDIED BY UTILIZING THE TRANSIENT ABSORPTION SPECTROSCOPY AND Z-SCAN TECHNIQUES. THE OBSERVED ULTRAFAST CARRIER RELAXATION DYNAMICS OF GO AND REDUCED GO SHOWED TOTALLY DIFFERENT BEHAVIORS, WHICH INSPIRED US TO INV