Comparative Analysis of Optical Spectra of Plasmonic Nanoparticles of Different Geometrical Shapes
- PDF / 786,090 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 46 Downloads / 175 Views
arative Analysis of Optical Spectra of Plasmonic Nanoparticles of Different Geometrical Shapes A. V. Mekshuna,*, S. S. Moritakaa,**, A. D. Kondorskiia,***, and V. S. Lebedeva,**** a
Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 Russia *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected] ****e-mail: [email protected] Received March 25, 2020; revised June 25, 2020; accepted June 26, 2020
Abstract–Numerical calculations and a comparative analysis of light extinction spectra of single silver nanoparticles shaped as sphere, rod, dumbbell, disk, and triangular prism are performed using the FDTD method. The strong dependence of the results for intensities and positions of maxima of localized plasmon resonance peaks on the geometrical shape of particles. Keywords: nanoplasmonics, extinction spectra, silver nanoparticles, localized plasmon resonances DOI: 10.3103/S1068335620090031
INTRODUCTION The intensive development of nanoplasmonics in the last two decades is caused by its numerous applications for solving a number of fundamental problems of near-field optics and for developing various photonic and optoelectronic devices. Localized surface plasmons are excited in metal nanoparticles [1–4] and metal-containing nanostructures [5–8] and represent collective inphase oscillations of the charge density, bounded on the metal nanoparticle surface. Therefore, their properties depend strongly on sizes and geometrical shape of the metal structure. When the external electromagnetic field frequency coincides with one of eigenfrequencies of plasma oscillations, the localized surface plasmon resonance phenomenon is observed, which arises due to consistent motion of conduction electrons interacting with field. The phenomenon consists in a significant increase in the local field strength near the nanoparticle in comparison with the external field strength; therefore, light absorption and scattering cross sections sharply increase at field frequencies close to the plasmon resonance peak frequency. STUDY OBJECTIVE AND CALCULATION PROCEDURE The objective of this study is to perform numerical calculations of the extinction cross sections of silver nanoparticles of different geometrical shapes and a comparative analysis of the results obtained for intensities and positions of maxima of spectral peaks of plasmon resonances. Calculations were performed for spherical, rod-shaped, and dumbbell-shaped nanoparticles, as well as for nanoplates with bases shaped as disks and equilateral triangles. For spherical particles, we used the Mie theory; for particles of more complex shape, the FDTD method was used. The method we used to calculate dielectric functions of silver nanoparticles taking into account the size effect is described in [9–11]. CALCULATION RESULTS AND DISCUSSION Figure 1 shows the normalized extinction cross sections σext of silver nanospheres in an aqueous solution, calculated by the Mie theory. The dependences of the cross sections σext on the light wavelength λ in vacu
Data Loading...
