MS - X04SA: Materials Science
| Energy range | 5 - 40 keV |
|---|---|
| Theoretical Flux (10 keV) | 1013 ph/s/0.4 A |
| Focused spot size | 160 µm x 32 µm (1:1 focussing) |
General description and specifications
The MS beamline is presently undergoing an upgrade to produce a high flux of hard X-rays from an undulator source, U14. A description of the new optical setup and source is available.The beamline sequentially serves two endstations, described briefly here:
Powder diffraction (PD)
Powder diffraction is performed in Experimental Hutch 1 (EH1). Responsible scientists are Nicola Casati and Antonio Cervellino. The MS Powder diffractometer has three coaxial independent angular motions, one for the sample (or sample environment) and the remaining two for independent detector systems:
- A unique solid-state silicon microstrip detector, called MYTHEN (Microstrip sYstem for Time-rEsolved experimeNts), an outstanding in-house PSI detector group development (Bernd Schmitt, group leader and Anna Bergamaschi, MYTHEN II development).
- A multicrystal-analyzer detector (employed only if really needed as acquisition times are much longer)
The second generation microstrip detector, MYTHEN II, consists of 30,720 Si-detector elements (50 micron strips, each subtending 0.0037 deg). The total subtended angle is 120o.
The MYTHEN detector is a general-purpose detector, with maximum resolution of 3.7 mdeg in 2θ, and very high efficiency and rapid acquisition times, with its simultaneous covering of 120 deg 2θ. This is the detector of choice for almost all experiments. This is especially true when either the scattering power is very low, or the acquisition times must be very short. It is therefore particularly suitable for time-resolved in-situ non-ambient XRPD and applications to the study of radiation sensitive materials, like organic compounds. MYTHEN is also ideal for Industrial Applications of XRPD , particularly in the field of pharmaceuticals. The multicrystal analyzer detector is the appropriate choice for ultra-high-resolution studies (below 2 mdeg in 2θ). The acquisition times are very disadvantageous, however, therefore this option is not recommended unless the sample quality is such that the higher resolution can be substantially beneficial.
Several sample environments are available at the MS-PD station, controlling sample temperatures from 4 K to 1800 K and high pressures as well, and interfaced with the MYTHEN acquisition software. For a detailed list see here.
At the MS-PD station it is also possible to perform SR-XRPD experiments in combination with neutron PD experiments, the latter performed at the PSI Neutron facility SINQ facility. Once a year, users can submit joint XRPD and neutron-PD proposals via the so-called X-rays and neutrons (x+n) channel and if the proposal is accepted, the joint X+n beamtime allocation is coordinated by the SLS and SINQ beamline scientists (Nicola Casati and Antonio Cervellino at the SLS-MS and Denis Sheptyakov and Vladimir Pomjakushin at SINQ) so to sequentially perform the experiments. The joint X+n user operation is now a mature project with regular calls on Feb 15 each year, beamtime is allocated whenever possible and not necessarily at the same time in the two facilities. It is presently limited to crystallographic applications and only involves the SLS-MS beamline Powder Station and the SINQ HRPT laboratory.
In-situ surface diffraction (SD)
In-situ surface diffraction is performed in Experimental Hutch 2 (EH2). The heart of the station is a large 2+3-circle surface diffractometer from Micro-Controle Newport, with two circles for the sample and three for the detector, plus a hexapod for precise alignment of the sample surface relative to the diffractometer axes. The diffractometer can be operated in two modes, either with a vertical, or a horizontal sample surface orientation.
The detector system is the PILATUS II novel photon-counting 2-D pixel detector, consisting of 486 x 195 pixels, each pixel subtending 0.0086o x 0.0086o. It also provides unsurpassed signal-to-noise ratios due to its zero electronic background noise, and has an excellent point spread function. The present maximum frame rate is 200 Hz.
Typical surface diffraction experiments include recording crystal truncation rods, superstructure rods, reflectivity curves, in-plane diffraction, grazing-incidence small-angle scattering experiments, and time-resolved studies.