Surface-Enhanced Raman Spectroscopic Studies of Oriented Monolayers on Electrode Surfaces

  • Yoon, Wan-Shik (Department of Applied Chemistry, Ajou University) ;
  • Im, Jung-Hyuk (Department of Applied Chemistry, Ajou University) ;
  • Kim, Jae-Ho (Department of Applied Chemistry, Ajou University)
  • Received : 1995.08.20
  • Published : 1995.12.25

Abstract

Monolayers of hypericin, a photodynamic polycyclic quinoidal compound, were prepared at the air-water interface, and were transferred to metal substrates to form Langmuir-Blodgett (LB) monolayers. The structural characteristics of hypericin LB monolayers and self-assembled (SA) monolayers were investigated using surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Both the spectroscopic data and the surface pressure - area (${\pi}-A$) isotherms suggest that hypericin forms ${\pi}-{\pi}$ aggregates that orient vertically to the subphase surface. Whereas the ordering and orientation of control was less effective in SA monolayers, a higher structural regularity was attained in LB systems. The effect of subphase on the structural integrity of the monolayer was also investigated.

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Acknowledgement

Supported by : Ajou University, Korean Research Foundation