Papers by Author: Munetaka Oyama

Abstract: This paper reports the study on the shape effect of gold nanoparticles on their plasmonic responses to the vapor samples, such as methanol, ethanol and propanol. In typical process, it was observed that the plasmonic of gold nanoparticles was very sensitive to the presences of the vapor samples by giving the change in the absorption as well as the shift in the SPR peaks position. It was also found that the plasmonic responses to the vapor indicated a significant improved if the gold nanoparticles prepared in the form of nanorods morphology. The plasmonic response of the spherical and nanorods gold nanoparicles to the gasses will be discussed.

Abstract: This paper reports the preparation of exceptionally high brightness CdTe quantum dots (QDs) that gives emission in the range of green to red by simply prepared them in a binary mixture of octadecyl phosphonic acid (ODPA) and oleic acid (OA) surfactants. By easy controlling the ratio between the two surfactants in the reaction, the QDs with unique emission, high -brightness and -quantum yield (QY), ca. 63, 87 and 89% for green, yellow and red QDs respectively, can be obtained. Owing to their unique PL and high QY, the CdTe QDs should find an extensive uses in the currently existing applications.

Abstract: Applying a bicolor coherent treatment of a Nd-YAG laser with wavelength 1.32 μm and its second harmonic generation, we have investigated photoinduced SHG in Au nanoparticledeposited ZnO nanocrystallinne (NC) films. We have established that coexistence of the such crystallites gives substantially better results compared to the pure ZnO NC deposited onto the glass substrate. It was shown that the value of the second order susceptibility obtained for the large incident angles of the fundamental and writing beams is equal to about 23 pm/V. The better results are obtained during the phototreatment at temperatures near the 60 oC for the Au doped samples and is almost non-sensitive to temperature for the pure samples. The further increase of the temperature leads to decay of the optical second harmonic generation