Size-dependent Raman spectroscopic Studies of Nonometer-sized Diamonds

• Main Authors: Kuo-Yen Tang, 唐國硯
• Other Authors: Wen-Ku Chang
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/93885298248601262362

碩士 === 國立東華大學 === 材料科學與工程學系 === 92 === In this research, the nano-meter sized diamond (average ~100nm and 5nm in diameter) are studies in our laboratory using FTIR and Raman spectroscopy in an effort to reproduce the observed interstellar unidentified bands (UIB). The infrared spectrum of well hydrogenated nanometer sized diamond surface reveals it is identical to the IR spectra observed from star systems of HD 97048 and Elias 1. The result provides a trusty evidence for the identification of interstellar spectra. The characteristic absorptions of the infrared spectra are assigned to CH stretching on nanodiamond surface. To better understand the UIB, we decompose ethylene onto well-hydrogenated nanodiamonds surface, then thermal annealing gradually at elevated temperatures in vacuum, and compare the obtained infrared spectra in the laboratory with UIBs spectra, the result indicates that the absorption at 3050 cm-1 can be attributed to aromatic CH stretching on nanodiamonds surface. The finding supplies more information about HD97048 and the obtained infrared and Raman spectra gives further understanding of the infrared spectra of the interstellar medium. In the past, there were many size-dependence infrared spectroscopic experiments on diamonds. However, size- dependent Raman spectroscopic studies have been limited. We found that atomic hydrogen etching has different influence on 100 nm and 5 nm diamonds structure. Due to grain sizes, result on 100nm diamonds implies the graphitization on the surface structures have much change; for 5nm diamonds, it completes graphitization at fixed thermal annealing time with and without atomic hydrogen even though we prolong the annealing time. In addition, there are many arguments about ~1150 cm-1 Raman shift, we use thermal annealing with and without atomic hydrogen to compare it with DLC. Due to atomic hydrogen etching, its intensities significantly change and graphitize; that is to say, sp2 bonding structure appears on the surface due to hydrogen etching. From that, we assign it to trans-polyacetylene in the grain boundaries.