Sum frequency generation spectroscopy of ultrathin biomolecular films on enhanced by visible surface plasmon excitation

Strong enhancement of an electric field at the metal-dielectric interface due to the visible surface plasmon-polariton (SP) excitation can be achieved both for linear and for nonlinear spectral measurements. This effect is used to increase the SFG yield of ultrathin biomolecular (thiopeptide) monolayer film on the gold surface. Using the optical scheme with co-propagating infrared and visible laser beams and the prism SP excitation (in Kretschmann configuration) can significantly enhance the SFG output due to the excitation of two SPs at visible laser and SFG frequencies simultaneously.