Time-Resolved Photoluminescence in Gold Nanoantennas

Abstract

We present spectrally and time-resolved measurements of one-photon and multiphoton photoluminescence from gold nanoantenna arrays. In the literature, very different emission decay rates have been observed: while some authors find a very short decay rate (<50 fs), others report the presence of long-lived components (from a few picoseconds up to a few nanoseconds). Accordingly, different interpretations of the related physical mechanisms have been tentatively drawn. Our work demonstrates a decay rate of less than 500 fs (as limited by our temporal resolution) in the weak-perturbation regime, which can increase up to a few picoseconds with higher excitation fluences. This confirms that the decay dynamics of the photoluminescence process is influenced by electron thermalization in the conduction band, especially at higher excitation fluences for which high temperatures of the electron gas are reached. On the contrary, no experimental evidence of longer-lived nanosecond components is observed.