Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the formation and decay of a molecular ultracold plasma   Double-resonant photoexcitation of nitric oxide in a molecular beam creates a
dense ensemble of $50f(2)$ Rydberg states, which evolves to form a plasma of
free electrons trapped in the potential well of an NO$^+$ spacecharge. The
plasma travels at the velocity of the molecular beam, and, on passing through a
grounded grid, yields an electron time-of-flight signal that gauges the plasma
size and quantity of trapped electrons. This plasma expands at a rate that fits
with an electron temperature as low as 5 K, colder that typically observed for
atomic ultracold plasmas. The recombination of molecular NO$^+$ cations with
electrons forms neutral molecules excited by more than twice the energy of the
NO chemical bond, and the question arises whether neutral fragmentation plays a
role in shaping the redistribution of energy and particle density that directs
the short-time evolution from Rydberg gas to plasma. To explore this question,
we adapt a coupled rate-equations model established for atomic ultracold
plasmas to describe the energy-grained avalanche of electron-Rydberg and
electron-ion collisions in our system. Adding channels of Rydberg
predissociation and two-body, electron- cation dissociative recombination to
the atomic formalism, we investigate the kinetics by which this relaxation
distributes particle density and energy over Rydberg states, free electrons and
neutral fragments. The results of this investigation suggest some mechanisms by
which molecular fragmentation channels can affect the state of the plasma.

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The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: cs
36
The categories of this paper are: cmp-lg