THz- and laser-induced Molecular Orientation

In the case of linear molecules, the laser-induced orientation is transient and disappears shortly after the excitation, typically within several hundreds of femtoseconds. The question is whether a long-lasting orientation is possible, i.e., on a nanosecond time scale or even longer. The answer is yes, but only for non-linear molecules, the so-called symmetric- or asymmetric-tops.

    Laser Control of Chiral Molecules

    Differentiation and separation of molecular enantiomers in a mixture are important and challenging problems. While many physical properties are identical in the two enantiomers, their biological activities are often markedly different. We use strong nonresonant laser fields with twisting polarization to selectively control the rotations of chiral molecules in the gas phase.

    Polarization Drag: Mechanical Faraday Effect

    When linearly polarized light is transmitted through a rotating dielectric, the polarization plane is slightly rotated—a phenomenon first studied by Fermi in 1923. We showed that this effect may be dramatically enhanced if the light is sent to a gas of fast unidirectionally spinning molecular super-rotors.

    Echo Phenomena in Molecular and Quantum Optical Systems

    Echo in mountains is a well-known phenomenon, where an acoustic pulse is mirrored by the rocks, often with reverberating recurrences. Over the years, we studied various echo phenomena in the rotational and vibrational dynamics of laser-excited molecular gases, and in other quantum systems.

    Imaging of Coherent Molecular Rotation

    Several techniques for producing molecular movies have been proposed based on the Coulomb explosion to follow the ultrafast rotational dynamics in real time.We demonstrate a novel nondestructive optical method for direct visualization and recording of movies of coherent rotational dynamics in molecular gas.

    Guiding Molecules in Space

    Molecules, unlike atoms, have an anisotropic shape, and their interaction with external fields depends on the orientation of the molecule with respect to the field and its gradient. We study how the deflection of molecules by external fields can be manipulated using additional laser pulses.

    Super Rotors and Vortices

    The possibility of creating molecules excited to extremely high rotational states (super rotors) enables us to explore new kinetic effects in molecular gases, including the creation of gas vortices.