Berlin 2014 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 45: Velocity map imaging - focusing on intra- and interatomic dynamics SYPS 2 (with jDPG)

A 45.1: Hauptvortrag

Donnerstag, 20. März 2014, 16:30–17:00, Audimax

Unraveling the dynamics of state- and conformer selected molecules fixed in space with the VMI — •Jochen Küpper — Center for Free-Electron Laser Science, DESY, Hamburg — Department of Physics, University of Hamburg — The Hamburg Center for Ultrafast Imaging, Hamburg

Velocity-map imaging (VMI) provides a powerful detection scheme for the dynamics of complex molecules. In this tutorial, I will introduce the methods to spatially separate different species present in molecular beams, to fix these molecules in space, and to investigate their structures and dynamics using VMI.

Inhomogeneous electric fields enable the spatial separation of conformers (structural isomers), nuclear spin isomers, and individual quantum states. These experiments exploite the neutral-molecule analogues of the electric bender, the ion guide, and the linear accelerator. The created state-selected molecular samples provide unprecedented options to fix molecules in space. The VMI spectrometer allows to unravel the resulting rotational dynamics of molecules in the applied electric and laser fields of vastly different strength and duration. The detailed analysis of these rotational dynamics and the prepared pendular states is an instructive example of quantum control.

VMI is also used to image photoelectron angular distributions (PAD). Utilizing the described controlled samples one can observe molecular frame (MF) PADs that provide direct images of electronic and geometric structures of molecules, potentially with femtosecond time resolution.