Control of molecular alignment and orientiation

The physical and chemical properties of molecules measured in gas or liquid pase usually reflect an averaging over isotropic angular distributions. By controlling the rotational degrees of freedoms one can narrow these distributions which is of paramount importance for many fields, e. g. for molecular imaging techniques. The most successful approach to align molecules is based on the  interaction of the anisotropic molecular polarizability with intense, pulsed laser fields.

 

In our work we model the dynamics of controlled molecular rotations in terms of quantum-mechanical pendular states for which semi-analytical results can be derived. Further, we investigate intensity,  temperature, and  pulse length effects on the control of molecular rotational degrees of freedom, ranging between the limits of adiabatic and non-adiabatic (field-free) alignment. In other work, we extend this concept to the situation of molecules in dense gases and in sold crystals, thus exploring the limits of light-induced alignment and/or orientation.

 

The project has been funded through the SFB 450 "Analysis and control of ultrafast photoinduced reactions".

Selected Publications

  • Intense-Field Alignment of Molecules Confined in Octahedral Fields T. Kiljunen, B. Schmidt, N. Schwentner Phys. Rev. Lett. 94 (12), 123003 (2005)

 

  • Quantum Dynamics of a Plane Pendulum M. Leibscher, B. Schmidt Phys. Rev. A 80 (1), 012510 (2009)

 

 

  • State Selection in Non-Resonantly Excited Wave Packets by Tuning from Non-Adiabatic to Adiabatic Interacti N. Owschimikow, B. Schmidt, N. Schwentner Phys. Rev. A 80 (5), 053409 (2009)

 

 

  • Laser-induced alignment and anti-alignment of rotationally excited molecules. Owschimikow, N. and Schmidt, B. and Schwentner, N. Phys. Chem. Chem. Phys. 13 (19), pp. 8671-8680 (2011)

 

  • Fragmentation due to centrifugal forces in the photodissociation of H2+ in intense laser fields. Fischer, M. and Lorenz, U. and Schmidt, B. and Schmidt, R. Phys. Rev. A 84 (3), 033422 (2011)

 

  • Cross sections for rotational decoherence of perturbed nitrogen measured via decay of laser-induced alignment. Owschimikow, N. and Königsmann, F. and Maurer, J. and Giese, Ph. and Ott, A. and Schmidt, B. and Schwentner, N. J. Chem. Phys. 133 (4), 044311 (2010)

Head:

Christof Schütte

Project researchers

Burkhard Schmidt

 

Cooperations: Nina Owschimikow, Monika Leibscher, Prof. N. Schwentner (Dept. of Physics, FU Berlin)