Abstract
The size and temperature dependences of the surface plasmon energy are studied for silver nanoparticles embedded in a silica host matrix in the size range 11–30 nm and in the temperature interval 293–650 K. It is revealed that the surface plasmon energy in studied silver nanoparticles depends on the size and the temperature of nanoparticles. As the size of nanoparticles decreases or the temperature increases, the surface plasmon resonance shifts to the red side.When the size of nanoparticles decreases, the rate of scattering of the conduction electrons on the nanoparticle surface increases, which results in a nonlinear red shift of the surface plasmon resonance. The temperature dependence of the red shift is linear for larger nanoparticles and becomes nonlinear for smaller ones. It is shown that the volume thermal expansion of nanoparticles leads to a red shift of the surface plasmon resonance, as the temperature increases. It is revealed that the thermal volume expansion coefficient depends on the size and the temperature. It increases with decrease of the nanoparticle size and with increase of the temperature.
Highlights
We present experimental results on the size and temperature dependence of the Surface Plasmon Resonance (SPR) energy in silver nanoparticles embedded in silica
We use the theory outlined above to explain the experimental dependences of the SPR energy on the temperature and the size of silver nanoparticles
The SPR energy in silver nanoparticles embedded in a silica glass host matrix depends on the size and the temperature of nanoparticles
Summary
Noble metal nanoparticles have attracted a lot of attention recently due to a wide range of potential applications in Surface Enhanced Raman Scattering (SERS) [1,2,3], surface enhanced fluorescence [4,5,6], biochemical imaging [7,8,9], cancer treatment [7, 10,11,12], and subwavelength optical waveguides [13,14,15,16,17], to name just a few. The size confinement of conduction electrons is the factor that influences considerably the optical and electronic properties of metal nanoparticles [18,19,20,21] Size effects influence both the position and the width of the collective coherent excitation of free electrons, known as the Surface Plasmon Resonance (SPR) band [18, 19, 22]. In addition to the size effect, the increase of the temperature of nanoparticles leads to an additional shift of the SPR band and its broadening [18].
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