Physical Review X (Oct 2013)

Rotational Coherence Encoded in an “Air-Laser” Spectrum of Nitrogen Molecular Ions in an Intense Laser Field

  • Haisu Zhang,
  • Chenrui Jing,
  • Jinping Yao,
  • Guihua Li,
  • Bin Zeng,
  • Wei Chu,
  • Jielei Ni,
  • Hongqiang Xie,
  • Huailiang Xu,
  • See Leang Chin,
  • Kaoru Yamanouchi,
  • Ya Cheng,
  • Zhizhan Xu

DOI
https://doi.org/10.1103/PhysRevX.3.041009
Journal volume & issue
Vol. 3, no. 4
p. 041009

Abstract

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We investigate lasing action in aligned nitrogen molecular ions (N_{2}^{+}) produced in an intense laser field. We find that, besides the population inversion between the B^{2}Σ_{u}^{+}-X^{2}Σ_{g}^{+} states, which is responsible for the observed simulated amplification of a seed pulse, a rotational wave packet in the ground vibrational state (v=0) of the excited electronic B^{2}Σ_{u}^{+} state has been created in N_{2}^{+}. The rotational coherence can faithfully encode its characteristics into the amplified seed pulses, enabling reconstruction of rotational wave packets of molecules in a single-shot detection manner from the frequency-resolved laser spectrum. Our results suggest that the air laser can potentially provide a promising tool for remote characterization of coherent molecular rotational wave packets.