Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transient response of photoexcited electrons: negative and oscillating
  current   Time-dependent current of the electrons excited in the conduction band after
ultrafast interband photogeneration is studied theoretically. The transient
photocurrent is calculated for the nonlinear regime of response to a stationary
electric field. The response demonstrates transient absolute negative
conductivity when the electrons are excited slightly below the optical phonon
energy, while the periodic oscillations of the electric current appear after
formation of the streaming distribution. The quenching of these peculiarities
by the elastic scattering of electrons is also considered.

8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
2
The categories of this paper are: math
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex