Photoluminescence in Au film: Enhanced emission for a corrugated film

We perform experiments to observe photoluminescence (PL) from Au thin film deposited on a grating groove pattern etched in quartz substrate and also on the flat part of the substrate. The film is illuminated by ultraviolet light from the substrate side and the PL is detected from the film side. While no PL is detected for the plain film, emission with a broad spectrum (550-750 nm) is seen for the grating. The spectrum shows two dips with a systematic dependence on the grating period and sample orientation. Comparison of the PL and transmission spectral measurements show that the dips are associated with excitation of surface plasmons at the Au/air interface by the propagating light.