Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Length distribution of single walled carbon nanotubes determined by ac
  atomic force microscopy   A simple method to disperse individual single walled carbon nanotubes (SWCNT
) on an atomically flat substrate is presented. Proper tuning of ac modes of
atomic force microscopes(AFM) is discussed. This is needed to discriminate
between individual nanotubes and very small bundles. The distribution of
lengths of the nanotubes measured by these methods is reported.

22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
13
The categories of this paper are: quant-ph
15
The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an