Nanoplasmonics and surface enhanced spectroscopy

Plasmon phenomena in a metal nanotube of variable thickness
Malysh R.O.1, Korotun A.V.1
1 National University ”Zaporizhzhia Polytechnic“,
Zhukovskogo st., 64, Zaporizhzhia, Ukraine.
E-mail: andko@zp.edu.ua

Nowadays metal nanotubes due to the occurrence of surface plasmon resonances (PPR) are widely used, in particular, as optical sensors [1]. Note that if plasmon resonances in cylindrical metal shells are well studied (see, for example, [2]), then the question of excitation of PPR in metal shells of variable thickness is insufficiently studied. Therefore, the analysis of the influence of the nonconcentricity of the shell boundaries on the PPR frequencies in the optical frequency range is an urgent task.
The approach to solving this problem consists of the following stages:
1) the electrostatic problem for determination of potentials in a cover, kernel and out of a cover is solved;
2) the polarizability of the studied nanostructure is determined;
3) PPR frequencies are determined from the condition of zero of the real part of the denominator of the expression for polarizability.
Note that knowing the polarizability, it is possible to determine such observed quantities as the absorption and scattering cross sections of a metal nanotube of variable thickness.
The study of the frequency dependences of the porosity showed the presence of additional resonances caused by the nonconcentricity of the shell boundaries. In addition, it was found that the absorption and scattering cross sections significantly depend on the amount of shear of the centers of the dielectric nucleus and the entire nanotube.

1.	Klimov V. V. Nanoplasmonics, Boca Raton, FL: CRC Press, Taylor and Francis Group, 2014, 581 p.
2.	Korotun A. V., Karandas Ya. V. Surface Plasmons in a Nanotube with a Finite-Thickness Wall // Phys. Met. Metallogr., 2022.-123.-No. 1.- P. 7–15.