Imaging aligned OCS molecules by laser induced electron diffraction

Summary form only given. One of the ultimate goals of molecular physics is the possibility of accessing the structural dynamics of molecules through external fields. To this end, one first has to image the molecular structure and dynamics with few-fs temporal resolution and atomic spatial resolution simultaneously. Laser induced electron diffraction (LIED) is a very promising candidate for the spatiotemporal imaging of small molecules [1]. So far most of the LIED experiments have been performed on isotropic molecular samples [2, 3]. Recently, this technique was used to derive C-C and C-H bond lengths of acetylene from a molecular-frame measurement [4]. Here, we present the investigation of the geometry of strongly aligned OCS molecules by using IR-driven laser induced electron diffraction. In our experimental setup, strongly aligned molecules are prepared in the interaction area by exploiting a combination of quantum-state-selected molecular beams and pulse-shaped laser fields. Molecular orientation can also be achieved by the application of an additional moderately strong DC electric field [5]. The controlled molecules are exposed to IR-driven LIED pulses. The LIED driving field consists of linearly polarised 50-fs pulses, with a tunable wavelength in the range 1.3-2.5 μm and an energy of few hundreds μJ (at 2.5 μm) or higher