Author: ["Omair Ghafur","Arnaud Rouzée","Arjan Gijsbertsen","Wing Kiu Siu","Steven Stolte","Marc J. J. Vrakking"]
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Abstract
A technique that produces significant alignment of molecules in a beam should aid a wide range of experiments geared towards understanding and controlling molecular processes in the gas phase. Manipulation of the molecular-axis distribution is an important ingredient in experiments aimed at understanding and controlling molecular processes1,2,3,4,5,6. Samples of aligned or oriented molecules can be obtained following the interaction with an intense laser field7,8,9, enabling experiments in the molecular rather than the laboratory frame10,11,12. However, the degree of impulsive molecular orientation and alignment that can be achieved using a single laser field is limited13 and crucially depends on the initial states, which are thermally populated. Here we report the successful demonstration of a new technique for laser-field-free orientation and alignment of molecules that combines an electrostatic field, non-resonant femtosecond laser excitation14 and the preparation of state-selected molecules using a hexapole2. As a unique quantum-mechanical wavepacket is formed, a large degree of orientation and alignment is observed both during and after the femtosecond laser pulse, which is even further increased (to 〈cosθ〉=−0.74 and 〈cos2θ〉=0.82, respectively) by tailoring the shape of the femtosecond laser pulse. This work should enable new applications such as the study of reaction dynamics or collision experiments in the molecular frame, and orbital tomography11 of heteronuclear molecules.Cite this article
Ghafur, O., Rouzée, A., Gijsbertsen, A. et al. Impulsive orientation and alignment of quantum-state-selected NO molecules. Nature Phys 5, 289–293 (2009). https://doi.org/10.1038/nphys1225 