Penetration-Depth Characteristics of Evanescent Fields at Metal Attenuated Total Reflection

Evanescent waves generated on a metal surface at attenuated total reflection (ATR) were detected with a fluorescent-dye-coated probe tip. The field intensity of the metal ATR evanescent waves is considerably larger than that of total internal reflection (TIR) evanescent fields on a dielectric surface, but the ATR-field penetration depth depends only upon the incident angle of excitation light at a fixed wavelength; at the same incident angle, it is nearly the same value as that of the TIR fields.