A measurement of evanescent fields generating on metal thin films and Langmuir-Blodgett ultrathin films

Surface plasmons (SPs) were resonantly excited for aluminum (Al) thin films and arachidate acid (C20) LB ultrathin films on the substrates in a Kretsc hmann configuration of the attenuated total reflection (ATR) method. Evanes cent fields generating on the Al thin films and the LB films due to excitat ions of the SPs were detected as luminescent light from a metallic needle p robe covered with CdS in the localized evanescent fields. The luminescent l ight, that is, the evanescent fields were measured as a Function of the inc ident angle of the laser beam exciting the SPs and as a function of the dis tance from the surface. The luminescent light intensity was biggest at a lo wer angle than the resonant angle. These properties were calculated and dis cussed. Evanescent fields were also measured for C20 LB films on Al thin fi lms.