Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Motional Averaging of Nuclear Resonance in a Field Gradient   The traditional view of nuclear-spin decoherence in a field gradient due to
molecular self-diffusion is challenged on the basis of temperature dependence
of the linewidth, which demonstrates different behaviors between liquids and
gases. The conventional theory predicts that in a fluid, linewidth should
increase with temperature; however, in gases we observed the opposite behavior.
This surprising behavior can be explained using a more detailed theoretical
description of the dephasing function that accounts for position
autocorrelation effects.

37
The categories of this paper are: supr-con
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas