TY - JOUR A1 - Duva, G. A1 - Pithan, L. A1 - Zeiser, C. A1 - Reisz, B. A1 - Dieterle, J. A1 - Hofferberth, B. A1 - Beyer, P. A1 - Bogula, L. A1 - Opitz, A. A1 - Kowarik, Stefan A1 - Hinderhofer, A. A1 - Gerlach, A. A1 - Schreiber, F. T1 - Thin-Film Texture and Optical Properties of Donor/Acceptor Complexes. Diindenoperylene/F6TCNNQ vs Alpha-Sexithiophene/ F6TCNNQ N2 - In this work, two novel donor/acceptor (D/A) complexes, namely, diindenoperylene (DIP)/1,3,4,5,7,8-hexafluoro-tetracyanonaphthoquinodimethane (F6TCNNQ) and alpha-sexithiophene (6T)/F6TCNNQ, are studied. The D/A complexes segregate in form of π−π stacked D/A cocrystals and can be observed by X-ray scattering. The different conformational degrees of freedom of the donor molecules, respectively, seem to affect the thin-film crystalline texture and composition of the D/A mixtures significantly. In equimolar mixtures, for DIP/F6TCNNQ, the crystallites are mostly uniaxially oriented and homogeneous, whereas for 6T/F6TCNNQ, a mostly 3D (isotropic) orientation of the crystallites and coexistence of domains of pristine compounds and D/A complex, respectively, are observed. Using optical absorption spectroscopy, we observe for each of the two mixed systems a set of new, strong transitions located in the near-IR range below the gap of the pristine compounds: such transitions are related to charge-transfer (CT) interactions between donor and acceptor. The optical anisotropy of domains of the D/A complexes with associated new electronic states is studied by ellipsometry. We infer that the CT-related transition dipole moment is perpendicular to the respective π-conjugated planes in the D/A complex. KW - Optical properties KW - Molecular semiconductor KW - X-ray diffraction PY - 2018 DO - https://doi.org/10.1021/acs.jpcc.8b03744 SP - 18705 EP - 18714 PB - ACS AN - OPUS4-46400 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kowarik, Stefan A1 - Bogula, A1 - Boitano, A1 - Carla, A1 - Pithan, A1 - Schafer, A1 - Wilming, A1 - Zykov, A1 - Pithan, T1 - A novel 3D printed radial collimator for x-ray diffraction N2 - We demonstrate the use of a 3D printed radial collimator in X-ray powder diffraction and surface sensitive grazing incidence X-ray diffraction. We find a significant improvement in the overall Signal to background ratio of up to 100 and a suppression of more than a factor 3⋅10⁵ for undesirable Bragg reflections generated by the X-ray “transparent” windows of the sample environment. The background reduction and the removal of the high intensity signals from the windows, which limit the detector’s dynamic range, enable significantly higher sensitivity in experiments within sample environments such as vacuum chambers and gas- or liquid-cells. Details of the additively manufactured steel collimator geometry, alignment strategies using X-ray fluorescence, and data analysis are also briefly discussed. The flexibility and affordability of 3D prints enable designs optimized for specific detectors and sample environments, without compromising the degrees of freedom of the diffractometer. KW - 3D printing PY - 2019 DO - https://doi.org/10.1063/1.5063520 SN - 0034-6748 VL - 90 IS - 3 SP - 035102, 1 EP - 8 PB - AIP AN - OPUS4-48171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -