Dr. Vinod Kumarappan
Kansas State University, Department of Physics
Alignment and Orientation of Molecules with Lasers: A Quest for the Molecular Frame
102 Cardwell Hall
September 16, 2013
The interactions of molecules with each other and with external fields depend on their relative orientation, but often this aspect is obscured by thermal rotational motion. In this Colloquium I will describe our efforts to control the orientation of gas-phase molecules using strong non-resonant laser fields with the goal of making measurements in the molecular frame. These include one-dimensional alignment and orientation of linear molecules and three-dimensional alignment of asymmetric top molecules. I will also discuss how the angle dependence of photo-induced processes can be obtained using pump-probe measurements from a rotational wave-packet. These techniques provide us with access to molecular frame information that is, especially for asymmetric tops, currently unattainable by any other means. As examples, I will describe how we extract
angle-dependent photo-ionization rates in nitrogen and ethylene from high harmonic generation and ion yield measurements, respectively.