釕的黃銅礦物質以及三元混晶硫化釕鐵之拉曼特性研究

Abstract

我們用良好的鑑別率和較寬的波長範圍測量碲化釕的拉曼訊號。其結果與 硫化釕、硒化釕比較，我們發現它們的聲子頻率與銅素（ 硫、硒、碲 ） 質量倒數的平方根形成線性關係。此外，由共振拉曼散射的研究之中我們 可以得到釕的黃銅礦物質電子態之間的躍遷能量。類似的研究亦用在三元 混晶硫化釕鐵之中。我們發現由於鐵離子的磁性，所以在此一混晶系統之 中鐵原子的影響比釕原子來得大。當釕和鐵成份的比例由非常懸殊變成比 例相當時，原本硫化釕或硫化鐵的Ag與Eg聲子模線寬會變寬。在比例各占 百分之五十的時候，其振動模式混合在一起形成一個混合模。我們選用五 種不同波長（457.9-647.1 nm）的雷射重覆實驗，得到了相同的結果。從 聲子頻率隨濃度的變化可知道此一系統並不同於 one-mode 及two- mode 的行為。我們也研究混晶系統的拉曼共振效應。另外，從空間相關模型來 模擬混晶光譜的強度、線寬及不對稱，皆可以得到很好的吻合。 Raman scattering of single crystal RuTe2 has been carried out with good frequency resolution and wide wavelength coverage. The results were compared with other ruthenium compounds (RuS2, RuSe2) reported previously. We found a good linear relationship between all Raman shifts and the reciprocal chalcogen mass. Besides, resonant scattering for RuTe2, RuSe2 and RuS2 was observed which relates to inter- electronic-band transtions. Similar studies of the mixed magnetic semiconductors Ru1-xFexS2 had also been undertaen. We found that Fe atoms in the RuS2 lattice cause stronger perturbations than Ru atoms in the FeS2 lattice, because of the magnetic property of Fe2+ ions. As the Fe composition increases, the Raman modes begin to broaden and merge into only one peak at x=0.5. The x-dependence of the observed spectra shows mixed- mode behavior intermediate of one-mode and two-mode behavior. Raman enhancement is also present in the mixed crystal system. The asymmetric intensity broadening for x=0.2, 0.3 and 0.5 can be interpreted by the "spatial correlation" model.