Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thickness characterization of atomically-thin WSe$_2$ on epitaxial
  graphene by low-energy electron reflectivity oscillations   In this work, low-energy electron microscopy is employed to probe structural
as well as electronic information in few-layer WSe$_2$ on epitaxial graphene on
SiC. The emergence of unoccupied states in the WSe$_2$--graphene
heterostructures are studied using spectroscopic low-energy electron
reflectivity. Reflectivity minima corresponding to specific WSe$_2$ states that
are localized between the monolayers of each vertical heterostructure are shown
to reveal the number of layers for each point on the surface. A theory for the
origin of these states is developed and utilized to explain the experimentally
observed featured in the WSe$_2$ electron reflectivity.

31
The categories of this paper are: ao-sci
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
6
The categories of this paper are: astro-ph
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph