AVS 49th International Symposium
    Nanometer Structures Friday Sessions
       Session NS-FrM

Invited Paper NS-FrM3
ATR Vibrational Spectroscopy Towards Single Molecule Sensitivity and Molecular Level Spatial Resolution

Friday, November 8, 2002, 9:00 am, Room C-207

Session: Novel Surface Nanoprobes
Presenter: M. Futamata, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Correspondent: Click to Email
Recent developments in SPM (Scanning Probe Microscopy) or SXS (Surface X-ray Scattering) provide us atomic level information on structural changes at solid/liquid interfaces. However, it is in principle difficult to identify adspecies or to characterize interaction between adspecies and substrates even with these techniques. Vibrational spectroscopy gives valuable information on this point, if inherently low sensitivity is overcome. We have studied highly sensitive ATR (Attenuated Total Reflection)-IR and Raman spectroscopy utilizing surface plasmon polariton (SPP) with higher spatial resolution beyond diffraction limit by combining with SNOM (Scanning Near-field Optical Microscopy). Recently, ATR-IR spectroscopy allowed us to elucidate water molecules at hydrophobic SAM (Self-assembled monolayer)/solution interfaces, whose hydrogen-bond network are completely broken to give a sharp O-H stretching band at quite high-frequency region. In addition, amphiphilic organic nanotubes in solution substituting the water result in multilayer formation of the monomers. On single molecule characterization with micro-SERS (Surface Enhanced Raman Scattering) on Ag nanoparticles, we found the blinking (drastic intensity fluctuation with time) for adenine molecules without using electronic resonance effect. Raman image from aggregated Ag particles shows the parallel polarization to connecting axes gives significantly larger enhancement than perpendicular direction. These results are in good agreement with the theoretical evaluation of the local electric field using FDTD (Finite Difference Time Domain) method. (3) ATR-SNOM Raman spectroscopy utilizing SPP yields the enhancement of Raman signal up to 300 times and enables us to obtain the SNOM-Raman image with ca. 50 nm of spatial resolution.