架設Z-Scan量測技術並應用於強放光之異種金屬錯合物的雙光子吸收研究

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

林奕志(Yi-Chih Lin)

指導教授 ： 周必泰

國立臺灣大學/理學院/化學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10118

摘要

z-scan量測技術(Chapter 1)主要是將一道雷射光沿著樣品移動方向(z軸)聚焦並同時偵測光強度的改變，通常光強度的變化會是樣品在z軸位置的函數。假設如果在偵測器前面加上一個窄孔(我們通常稱呼為閉孔式裝置)，此時所偵測到的光強度變化會與光強度所造成的物質折射率改變相關，而物質折射率改變的會導致雷射光在焦點附近重新自聚焦或是自發散，這種現象主要是由三階非線性效應所引起。相對地，若偵測器前未加任何的孔並將所有的光都收集起來(我們通常稱呼為開孔式裝置)，此時所偵測到穿透光的強度變化會反應因光強度變化所造成的物質雙光子吸收。由以上的實驗裝置，我們可以簡單、快速且精準地測量物質本身的三階非線性效應及其物理量。
在本論文中，我主要是研究一系列金(I)-銅(I)、金(I)-銀(I)與銀(I)-銅(I)之異種金屬錯合物的光物理性質，並且利用自己所架設的z-scan量測技術測量其雙光子吸收特性(Chapter 3-7)。這些異種金屬錯合物主要都是經由自組裝結合而成，其光物理性質主要是具有很強的磷光放光性質，原因主要是因為metal-to-ligand charge transfer包含了中心的重金屬原子(如金、銀與銅)用以增強spin-orbit coupling，並造成強的磷光放光。更重要的是在有氧的情形下，這些磷光不具有oxygen quenching的效應，主要原因是在外圍的取代基太過於龐大，可以有效的保護電子在三重激發態時，不會被氧氣經由碰撞的形式代謝掉能量。同時間，我們也量測這些錯合物的雙光子吸收，結果顯示這些樣品不但具有強的磷光同時也具有較大的雙光子吸收係數(與一般的染料比較)。結合磷光與雙光子吸收這兩種性質，可提供這些樣品應用於時間解析影像與雙光子顯微技術的機會。

關鍵字

Z-scan量測技術 ； 雙光子吸收 ； 異種金屬錯合物 ； 金(I)-銅(I)錯合物 ； 金(I)-銀(I)錯合物 ； 銀(I)-銅(I)錯合物

並列摘要

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.

並列關鍵字

Z-scan technique ； two-photon absorption ； heterometallic complexes ； Au(I)-Cu(I) complexes ； Au(I)-Ag(I) complexes ； Ag(I)-Cu(I) complexes

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