Near- and Deep-Ultraviolet Resonance Raman Spectroscopy of Pyrazine−Al4 Complex and Al3−Pyrazine−Al3 Junction

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• 作者：Mengtao Sun ; Shunping Zhang ; Yurui Fang ; Zhilin Yang ; Deyin Wu ; Bin Dong ; Hongxing Xu
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：November 5, 2009
• 年：2009
• 卷：113
• 期：44
• 页码：19328-19334
• 全文大小：412K
• 年卷期：v.113,no.44(November 5, 2009)
• ISSN：1932-7455

文摘

Near- and deep-ultraviolet (UV) resonance Raman spectroscopy of pyrazine−Al₄ complex and Al₃−pyrazine−Al₃ junction was investigated theoretically with a quantum chemical method. Here, 325 and 244 nm were employed as near- and deep-UV sources in our theoretical study. The intensities of static normal Raman spectra of pyrazine−Al₄ complex and Al₃−pyrazine−Al₃ junction were enhanced on the orders of 10 and 10³ by a static chemical mechanism, respectively. The calculated absorption spectra reveal strong ⁶B₂ and ¹³B_2u electronic transitions near 325 nm for pyrazine−Al₄ complex and 244 nm for Al₃−pyrazine−Al₃ junction, respectively. The analyses of orbital transitions in electronic transitions reveal they are the mixture of (metal to molecule) charge transfer excitation and intracluster excitation. The intensity of near-UV resonance Raman spectroscopy of pyrazine−Al₄ complex and the intensity of deep-UV resonance Raman spectroscopy of Al₃−pyrazine−Al₃ junction are strongly enhanced on the order of 10⁵ and 10⁴, respectively, compared to the Raman intensity of isolated pyrazine excited at 325 and 244 nm. The calculations of Mie theory and the three-dimensional finite-difference time domain method reveal strong surface plasmon resonance and strong electromagnetic enhancements at 325 and 244 nm for single and dimer nanoparticles at suitable sizes and gap distance, respectively. The strongest SERS enhancement in the system of junction is on the order of 10⁸ at the incident lights of 325 and 244 nm. The total enhancements, including the chemical and electromagnetic enhancements, can reach up to 10¹³. So, Al is a suitable material for near- and deep-UV surface-enhanced resonance Raman scattering.