二氯化鍺之紫外光區螢光分光光譜研究

Dispersed fluorescence spectroscopy of the GeCl2 A ˜ –X ˜ transition

林鈺書(Yu-Shu Lin)

指導教授 ： 張伯琛

國立中央大學/理學院/化學系/碩士(2006年)

摘要

摘要

　　二氯化鍺（germanium dichloride, GeCl2）為半導體製作過程中產生的自由基分子。先前的文獻包含實驗及理論計算的研究皆著重在激發光譜的探討，對於某些熱譜帶的標示以及未知的譜帶有著不同的結論，另外因為基態振動參數是利用熱譜帶來決定，所以對於基態振動資訊的瞭解因缺少直接證據而不夠完整。本論文中利用高壓直流放電系統搭配超音速自由噴射裝置以及增強式電荷偶合偵測器，首次成功取得GeCl2 在紫外光區的螢光分光光譜，觀測能量從基態零點能延伸到7000 cm-1 ，不僅直接觀測到基態光譜並且獲得更多基態振動能階資訊，更從其中分辨出Ge35Cl2 、Ge35Cl37Cl 以及Ge37Cl2 三種同位素的譜帶。我們分別觀測到Ge35Cl2 84個基態振動能階，決定出對稱拉伸振動頻率（ ）、彎曲振動頻率（ ）、彎曲振動之非簡諧常數（ ）及對稱伸張-彎曲振動之非簡諧偶合常數（ ）等四個基態振動參數，在Ge37Cl2 的部分，觀測到18 個基態振動能階，決定了 ，此外也觀測到Ge35Cl37Cl 21個振動能階，除了決定 及 外，我們也觀測到基態非對稱拉伸振動頻率（ ），提供完整的基態振動能階資訊。在雷射誘導螢光光譜方面，藉由所取得的螢光分光光譜我們也成功的解釋於激發光譜上有爭議的熱譜帶標示，而對於未知譜帶的瞭解雖無直接證據可以解釋，但是實驗所得的結果也有重要的進展。

關鍵字

分子光譜 ； 二氯化鍺

並列摘要

Abstract
Germanium dichloride (GeCl2) is an important free radical in the process of producing semiconductors. The excitation spectrum contains several sharp peaks and a congested diffuse structure. Previous studies including experiments and theoretical calculation centered on the excitation spectrum, but have different conclusions about the assignments of hot bands and the unknown congested diffuse band. The laser-induced fluorescence excitation spectrum of the GeCl2 transition at ultraviolet wavelengths (300–320 nm) was recorded in a direct current discharge supersonic free jet expansion. Dispersed fluorescence spectra following the excitation of these GeCl2 ultraviolet bands were successfully acquired for the first time. The analysis of the dispersed fluorescence spectra reveals the detailed vibrational structure of the state. We have assigned the vibrational structures corresponding to different isotopomers (Ge35Cl2, Ge35Cl37Cl, and Ge37Cl2). The vibrational fundamental frequencies were determined: 409 cm−1 (symmetric stretch), 159 cm−1 (bend), and 352 cm−1 (antisymmetric stretch) for the state of GeCl2. Vibrational parameters of the ground electronic state including vibrational frequencies, anharmonicity, and bend-stretch coupling constant were determined. Our dispersed fluorescence spectra also clarify the vibrational assignments of the hot bands and provide more experimental data for unraveling the nature of the congested diffuse structure at shorter wavelengths in the excitation spectrum.

並列關鍵字

GeCl2 ； Dispersed fluorescence spectroscopy

參考文獻

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