Paper PL+BI-TuM13
Photo-Recognition and Control of a Small Number of Moleclues at Metal Nano-Gap Arrayed on Solid Surface

Tuesday, October 16, 2007, 12:00 pm, Room 619

Detection, recognition, and control of single molecules are a common theme in recent advanced technologies. It has been demonstrated that the surface-enhanced Raman scattering (SERS) phenomenon can drastically increase the scattering cross section, which is comparable to that of fluorescence at high quantum yield. Although the importance of single-molecule SERS (SM-SERS) has been well recognized from the early stage of its discovery, there are only a few examples supporting the observation of SM-SERS. In the present study, well-ordered, periodic metal nano-dot dimer arrays were prepared. The gap distance between two metal dots was optimized to show intense SERS in an aqueous solution. The system was also applied to control the adsorption of target molecules. In-situ Raman spectroscopic measurements with 785 nm excitation were carried out in aqueous solution using metal nano-gap array. Intense Raman signals were observed when the metal dimer structure was optimized. The SERS activity was dependent upon on the structure of the metal dimer with a distinct gap distance, suggesting that the intense SERS originates from the gap part of the dimer. Characteristic time-dependent spectral changes were observed both in Stokes and anti-Stokes region. In the system of Au dots array, relatively stable SERS signals was observed even under relatively strong photo-irradiation. Possibility of the molecular manipulation by electromagnetic filed will be discussed based on the characteristic behavior of SERS signals observed under relatively strong photo-irradiation.