Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Acoustic vibrations of a silica-embedded gold nanoparticle: elastic
  anisotropy   Spherical gold nanoclusters are grown by 1.8 MeV Au++ ion implantation into
an amorphous silica matrix and subsequent air annealing at 873 K. Ultraviolet
and visible light absorption confirms the presence of a dipolar surface plasmon
peak at the expected location for a gold sphere in silica. Grazing incidence
X-ray diffraction shows peaks corresponding to fcc gold with lattice spacing
close to that of bulk gold, as well as allowing estimation of cluster size
using Scherrer's formula. Low frequency Raman scattering reveals a relatively
narrow peak, suggesting a narrow distribution of nanocrystal diameters.
Acoustic phonon frequencies corresponding to the spheroidal quadrupolar
vibrations of a continuum sphere with the anisotropic elasticity of gold are
calculated using a novel method of molecular dynamics and extrapolation to the
continuum limit using relatively small numbers of point masses. The study
confirms high energy ion implantation as a method capable of producing gold
nanocrystals with spherical shape and well controlled size.

29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph