Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intensity dependence of multiple orbital contributions and shape
  resonance in high-order harmonic generation of aligned N$_{2}$ molecules}   We report measurements and theoretical simulations of high-order harmonic
generation (HHG) in aligned N$_2$ molecules using a 1200-nm intense laser field
when the generating pulse is perpendicular to the aligning one. With increasing
laser intensity, the minimum in the HHG spectra first shifts its position and
then disappears. Theoretical simulations including the macroscopic propagation
effects in the medium reproduce these observations and the disappearance of the
minimum is attributed to the additional contribution of HHG from inner
orbitals. We also predict that the well-known shape resonance in the
photoionization spectra of N$_2$ should exist in the HHG spectra. It is most
clearly seen when the generating laser is parallel to the aligning one, and
disappears gradually as the angle between the two lasers increases. No clear
evidence of this shape resonance has been reported so far when using lasers
with different wavelengths. Further experimentation is needed to draw
conclusions.

29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
5
The categories of this paper are: gr-qc
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
22
The categories of this paper are: chao-dyn
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
0
The categories of this paper are: hep-ph
8
The categories of this paper are: hep-ex