We report experimental results on the diffractive imaging of three-dimensionally aligned 2,5-diiodothiophene molecules. The molecules were aligned by chirped near-infrared laser pulses, and their structure was probed at a photon energy of 9.5 keV (λ ≈ 130 pm) provided by the Linac Coherent Light Source. Diffracted photons were recorded on the Cornell–SLAC pixel array detector, and a two-dimensional diffraction pattern of the equilibrium structure of 2,5-diiodothiophene was recorded. The retrieved distance between the two iodine atoms agrees with the quantum-chemically calculated molecular structure to be within 5%. The experimental approach allows for the imaging of intrinsic molecular dynamics in the molecular frame, albeit this requires more experimental data, which should be readily available at upcoming high-repetition-rate facilities.
At infinite resolution, cross-correlation terms between the individual molecules could theoretically be measured.
The scattering vector s is defined by s = sin(Θ)/λ, with the scattering angle Θ; therefore, 2Θ is defined between the axis of the XFEL and a point on the detector.
, where N is the total number of considered radial bins, n is x-value corresponding to a radial bin, y is the corresponding experimentally determined value with a standard deviation σ, and f(n) is the corresponding value from the simulated diffraction pattern.