Set-up of Z-scan Technique and Its Application in Two-photon Absorption of Heterometallic Complexes with Intensive Luminescence

• Main Authors: Yi-Chih Lin, 林奕志
• Other Authors: Pi-Tai Chou
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/05082908198768652052

碩士 === 國立臺灣大學 === 化學研究所 === 97 === The z-scan technique involves moving a sample along the path of a focused laser beam and measuring the light intensity at the detector as a function of its position along this z-axis (Chapter 1). If the detector has a narrow aperture (as in the so called “closed-aperture” setup), then the output is sensitive to intensity-dependent changes in the refractive index (as a result of third-order nonlinear polarizability or thermal effects) which lead to self-focusing or defocusing of the beam. Alternatively, if the detector collects all the light from the sample (“open-aperture” setup), then the output only reflects the intensity-dependent transmission, and can be used to measure two-photon absorption cross-sections. In this thesis, we studied the photophysical property and two-photon absorption cross-section for a series of AuI-CuI, AuI-AgI and AgI-CuI heterometallic alkynyl-diphosphine (diphosphine = PPh2-(C6H4)n-PPh2, n = 1, 2, 3) clusters (Chapter 3-7), which display a very intriguing structural pattern based on the heterometallic [AuxMy(C2Ph)2x]y-x fragments “wrapped” by the [Au3(diphosphine)3]3+ “belts”. As results, these complexes exhibit large two-photon absorption cross-sections and intense phosphores due to the transition involving metal-ligand charge transfer such that the heavy metal (Au) enhances spin-orbit coupling. More importantly, owing to fully protected chromophore by the bulky ancillary and bridging ligands, the phosphorescence is nearly inert to oxygen quenching. In combination the intensive phosphorescence intensity, minor O2 quenching property and the two-photon absorption property demonstrate these compounds with promising potential in two-photon emission imaging as well as phosphorescence dyes in time-resolved imaging.