Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical contrast of single- and multi-layer graphene deposited on a gold
  substrate   We study the optical contrast for single and multilayer graphene deposited on
a Au/SiO2/Si substrate. Our results prove that optical microscopy allows for
easy and quick localization, identification and counting of graphene layers.
Visibility depends on the thicknesses of the Au and SiO2 layers as well as the
wavelength of the light used. We propose optimum parameters for the detection
of graphene.

6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph