Time-Resolved X-ray Powder Diffraction Using a Large-Area CCD-Based Detector and Rietveld Refinement: Solid-State Polymerization of S2N2 to (SN)x

Abstract

A kinetic study of the solid-state polymerization of disulfur dinitride (S_~N2) to polysulfur nitride [(SN),] has been performed, combining monochromatic high-energy (~\ = 0.3263,~) synchrotron radiation X-ray powder diffraction, a large-area (o = 220 ram) CCD-based X-ray image-intensifier detector and Rietveld refinement. Recently developed techniques for detector calibration and reduction of two-dimensional images to one-dimensional diffraction patterns have been employed for data processing/analysis. Good fits were obtained after Rietveld refinement [Rp = 8.4%, wRp = 9.4%, sin(0.,,,~)/A = 0.585/~ 1] of diffraction patterns of S_~N_~ fiom images with 2 s exposure time. The solid-state polymerization of S2N_~ to (SN), was followed at a maximum rate of two diffraction images per minute. Scale factors and cell parameters for S,N~ and ,J-(SN), as functions o1" time were readily obtained after Rietveld refinement of the diffraction patterns obtained from each individual image throughout the polymerization. The polymerization was preceded by a lattice distortion of S2N~, and at 50% conversion the a axis had decreased by about 1% and the c axis had increased about 1%. The polymerization yielded not only the expected polymer ,~-(SN),, but also a small amount of a compound that could be another phase of (SN),.

The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source

“…Although CCDs (Svensson et al, 1997;Mezouar et al, 2005), image plates (Sarin et al, 2009) or a-Si flat panels (Lee, Aydiner et al, 2008) are often successfully employed, their limited dynamic range does not allow the correct observation of the intensity ratios between the strong and the weak reflections characterizing a powder pattern. In the following only photon-counting systems, which satisfy the requirements regarding the dynamic range (Lewis, 2003), will be discussed.…”

Fast X-ray powder diffraction on I11 at Diamond

“…However, temporal resolution is largely limited by the readout and erase times following each exposure, typically a few minutes per pattern. CCD-based pixel detectors, consisting of an input phosphor screen, image intensifier, optical lens coupling and camera, have been developed and applied at the ESRF (Svensson et al, 1997;Kvick, 2003) giving a collection rate of 100 ms per frame for in excess of 100 frames (Kvick, 2003). Wide-angle multi-wire gas proportional detectors were originally developed at the NSLS and used on beamline X7A (Smith, 1991), with a similar device being developed at the Daresbury SRS and used on beamline MPW6.2 (Cernik et al, 2004;Tang et al, 2004).…”

A time-resolved powder diffraction study of in-situ photodimerization kinetics of 9-methylanthracene using a CCD area detector and parametric Rietveld refinement

“…with preferred orientation and/or large grain size, single-crystal spots etc.) and in-situ studies (Svensson et al, 1997).…”