A theory of intense-field dynamic alignment and high harmonic generation from coherently rotating molecules and interpretation of intense-field ultrafast pump-probe experiments

Abstract

A theory of ultra-fast pump-probe experiments proposed by us earlier [F.H.M. Faisal et al., Phys. Rev. Lett. 98, 143001 (2007) and F.H.M. Faisal and A. Abdurrouf, Phys. Rev. Lett. 100, 123005 (2008)] is developed here fully and applied to investigate the phenomena of dynamic alignment and high harmonic generation (HHG) from coherently rotating linear molecules. The theory provides essentially analytical results for the signals that allow us to investigate the simultaneous dependence of the HHG signals on the two externally available control parameters, namely, the relative angle between the polarizations, and the delay-time between the two pulses. It is applied to investigate the characteristics of high harmonic emission from nitrogen and oxygen molecules that have been observed experimentally in a number of laboratories. The results obtained both in the time-domain and in the frequency-domain are compared with the observed characteristics as well as directly with the data and are found to agree remarkably well. In addition we have predicted the existence of a "magic" polarization angle at which all modulations of the harmonic emission from nitrogen molecule changes to a steady emission at the harmonic frequency. Among other things we have also shown a correlation between the existence of the "magic" or critical polarization angles and the symmetry of the active molecular orbitals, that is deemed to be useful in connection with the "inverse problem" of molecular imaging from the HHG data.

31 pages, 22 figures, and 140 equations

References in corpus (5)

• The Evolution and Revival Structure of Localized Quantum Wave Packets
• Strong-field ionization of diatomic molecules and companion atoms: strong-field approximation and tunneling theory including nuclear motion
• High-harmonic generation from arbitrarily oriented diatomic molecules including nuclear motion and field-free alignment
• Effects of orientation and alignment in high-harmonic generation and above threshold ionization
• Interplay of polarization geometry and rotational dynamics in high harmonic generation from coherently rotating linear molecule

Cited by in corpus (6)

• Quantitative Rescattering Theory for high-order harmonic generation from molecules
• The Impact of Multichannel and Multipole Effects on the Cooper Minimum in the High-Harmonics Spectrum of Argon
• Ultrafast Molecular Imaging by Laser Induced Electron Diffraction
• Theoretical Study of Molecular Electronic and Rotational Coherences by High-Harmonic Generation
• General phenomenology of ionization from aligned molecular ensembles
• Dynamics of fluctuations in a quantum system