Reversible tuning of surface plasmon resonance of silver nanoparticles using a thermochromic matrix

Reversible tuning of surface plasmon resonance (SPR) of Ag nanoparticles by temperature was achieved using a thermochromic VO2 as matrix. The SPR wavelength (lambda(SPR)) was significantly shifted from 506 nm for Ag on sapphire to 1070 nm for Ag embedded in VO2 at room temperature, giving a large sensitivity factor (Delta lambda(SPR)/Delta n) of approximate 352 nm per refractive index (n) unit. The lambda(SPR) of Ag in VO2 can be changed reversibly and easily by heating-cooling circles between lambda(SPR)=1070 nm at 20 degrees C and lambda(SPR)=844 nm at 90 degrees C, a tunable wavelength range of as large as 226 nm only by changing the temperature. The reversible change of refractive index of thermochromic VO2 matrix upon temperature is responsible for this lambda(SPR) tuning. (C) 2006 American Institute of Physics.