X-ray diffractive imaging of controlled gas-phase molecules

Diffractive imaging of aligned and oriented gas-phase molecules is a promising tool to image molecular dynamics [1,2], such as isomerization, folding, or photofragmentation with femtosecond time and picometer spatial resolution. Here, we report of an experiment aiming at the structure determination of the prototypical large molecule 2,5-diiodothiophene (C4H2I2S) via x-ray diffraction. The experiment was conducted at the Coherent X-ray Imaging (CXI) beamline at the free-electron laser (FEL) Linac Coherent Light Source (LCLS). The molecules were non-adiabatically aligned at the full FEL repetition rate by chirped femtosecond laser pulses (pulse duration 94 ps) provided by the available in-house Ti:Sapphire laser system [3]. The molecular structure was probed with hard x-ray photons (130 pm, 9.5 keV), and the measured diffraction pattern will be discussed and compared to simulated diffraction patterns. An perspective for future experiments will be presented, including a discussion about pump-probe experiments at the upcoming high-repetition rate FELs (XFEL,LCLS II). The experiment was carried out in collaboration with the spokespersons F. Wang, J. Küpper, P. Bucksbaum, and H. Chapman. The collaboration consists of CFEL, PULSE, LCLS, European XFEL, Aarhus University, Kansas State University, Stanford University, and Uppsala University. Use of the LCLS, SLAC national accelerator laboratory, is supported by the US Department of Energy, Office of Science, and Office of Basic Energy Sciences.[1] Küpper et al. (53 authors), Phys. Rev. Lett. 122(8), 083002 (2014)[2] Barty, Küpper, Chapman, Ann. Rev. Phys. Chem. 64(1), 415-435 (2013)[3] Kierspel et al. (30 authors), J. Phys. B. 48(20), 204002 (2015