Two-pulse field-free orientation reveals anisotropy of molecular shape resonance

Abstract

We report the observation of macroscopic field-free orientation, i.e. more than 73 % of CO molecules pointing in the same direction. This is achieved through an all-optical scheme operating at high particle densities ($>10^{17}$cm${}^{-3}$) that combines a one-color ($\omega$) and a two-color ($\omega +2\omega$) non-resonant femtosecond laser pulses. We show that the achieved orientation solely relies on the hyperpolarizability interaction as opposed to an ionization-depletion mechanism thus opening a wide range of applications. The achieved strong orientation enables us to reveal the molecular-frame anisotropies of the photorecombination amplitudes and phases caused by a shape resonance. The resonance appears as a local maximum in the even-harmonic emission around 28~eV. In contrast, the odd-harmonic emission is suppressed in this spectral region through the combined effects of an asymmetric photorecombination phase and a sub-cycle Stark effect, generic for polar molecules, that we experimentally identify.

References in corpus (4)

• Photoelectron angular distributions from strong-field ionization of oriented molecules
• Laser-induced alignment and orientation of quantum-state-selected large molecules
• Field-free orientation of CO molecules by femtosecond two-color laser fields
• Mechanisms of two-color laser-induced field-free molecular orientation

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• Two-state wave packet for strong field-free molecular orientation
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• Laser induced persistent orientation of chiral molecules
• Correlation effects in strong-field ionization of heteronuclear diatomic molecules
• Time-dependent analysis of the mixed-field orientation of molecules without rotational symmetry
• Theoretical Study of Molecular Electronic and Rotational Coherences by High-Harmonic Generation
• Attosecond Molecular Spectroscopy and Dynamics
• Time delay of slow electrons by a diatomic molecule described by non-overlapping atomic potentials model
• Electron gun for diffraction experiments off controlled molecules