Discontinuous variation of the surface plasmon linewidth of small sodium nanoparticles with electron temperatures

¹ College of Physics and Electronic Information Engineering, Wenzhou University - Wenzhou 325035, PRC
² Department of Physics, Fudan University - Shanghai 200433, PRC

Received: 23 January 2015
Accepted: 29 April 2015

Abstract

We found a novel behavior of the surface plasmon linewidth of small sodium nanoparticles, which monotonically decreases with the electron temperature and bears a sudden drop or rise at high electron temperatures. Our calculation is based on the model constructed by splitting the total Hamiltonian of all valence electrons of a metallic nanoparticle into two sub-Hamiltonians and the coupling between them. This novel behavior of the surface plasma resonance linewidth can be verified by pump-probe femtosecond spectroscopy experiments and is able to take place for metallic particles with sizes less than few nanometers. In addition, we propose that it is the size uncertainty of small nanoparticles that yields the intrinsic linewidth of the surface plasmon resonance, which is supported by experimental and theoretical results of nanoparticles Na₈ and Na₂₀.