Strong-field molecular ionization: determination of ionization probabilities calibrated with field-free alignment

Ionization effects on field-free molecular alignment observed with high-order harmonic generation

“…According to previous studies, ionization gives rise to a heterodyned signal, leading to a modification of the transient shapes [13]. The presence of the free electrons in the gas changes the dispersion properties of the medium by providing an intensity-dependent index of refraction for the fundamental and the harmonic field.…”

“…Bellini et al [12] found that the conversion efficiency was modified by the depletion of the neutral atoms and defocusing of the pump beam. A ''cross-defocusing" method shown by Loviot et al [13,14] was employed to determine ionization probability calibrated through the degree of alignment. Kanai et al [5] reported the harmonic yields from aligned CO 2 molecules exhibit inverted modulation versus the field ionization and alignment parameter hcos 2 hi, this modulation inversion was attributed to the interference of recombination electrons from the two oxygen atoms in the CO 2 molecule.…”

Measurement of molecular polarizability anisotropy via alignment-induced spatial focusing and defocusing

“…In general, a homodyne detection, such as the weak field polarization technique [21] or cross-defocusing measurement [20], could only obtain a signal proportional to (δn) 2 or ( cos 2 θ -1/3) 2 , from which parallel and perpendicular alignment cannot be distinguished. Equation 2 shows that the τ-scan measurement…”

High rate concentration measurement of molecular gas mixtures using a spatial detection technique

“…It has been applied for instance to provide tomographic imaging of molecular orbitals, 7 to extract the phase of high harmonic generation, 8 to analyze the angular dependence of strong field molecular ionization, [9][10][11] or to determine ionization probabilities. 12,13 A theoretical report also proposed to exploit field-free molecular alignment in order to probe the collisions in dissipative media and determine the rate characterizing the elastic collisions. 14 In the present work, we explore the use of postpulse molecular alignment as a diagnosis tool to measure, with a single-shot ability, the concentration of a molecular gas mixture.…”