摘要
Rhodamine molecules are one of the most used dyes for applications related to Raman spectroscopy. We have systematically studied Raman spectra of Rhodamine 6G, Rhodamine 123, and Rhodamine B （RhB） molecules using density functional theory. It is found that with BP86 functional the calculated Raman spectra of cationic Rhodamine molecules are in good agreement with corresponding experimental spectra in aqueous solution. It is shown that the involvement of the counter ion, chlorine, and the specific hydrogen bonds has noticeable effects on the Raman spectra of RhB that can partially explain the observed difference between Raman spectra of RhB in solution and on gold surfaces. It also indicates that an accurate description of surface enhanced Raman scattering for Rhodamine molecules on metal surface still requires to take into account the changes induced by the interracial interactions.
基金
ACKNOWLEDGMENTS This work is supported by China Postdoctoral Science Foundation （No.2013M541951）. The Swedish National Infrastructure for Computing （SNIC） is acknowledged for computer time.
