Low Energy Wiggler Beamline (7-22 keV)


 

 

Measured performance

  • Energy range:                                       7 – 22 keV
  • Flux, @ 220 mA, minimum gap:         1012 photons/s with Si(111), or 1011 with Si(311)
  • Beam size, FWHM:                              Better than 150 μm V × 500 μm H
  • Energy resolution, ΔE/E:                    2.5 – 6.4 × 10-4
  • Divergence:                                           200 – 300 μrad V × 730 μrad H

 

Click here to download a pdf copy of the BXDS LE beamline paper

Leontowich, A. F. G., Gomez, A., Moreno, B. D., Muir, D., Spasyuk, D., King, G., Reid, J. W., Kim, C. Y., and Kycia, S. ‘The lower energy diffraction and scattering side bounce beamline for materials science at the Canadian Light Source.’ J. Synchrotron Rad., 28 (2021) 961-969

Endstations at the LE beamline operate at fixed energies, and support the following diffraction and scattering techniques,

  • "Huber" endstation, 15.1 keV, a 4 circle general purpose diffractometer. Optimized for high resolution powder diffraction. Also accommodates SAXS/WAXS, in-situ setups, reflectometry, reciprocal space mapping, and general diffraction
  • "IBM" endstation, 8.0 or 15.1 keV, optimized for in-situ rapid thermal annealing experiments on thin films and multilayer structures.

  

High-resolution powder X-ray diffraction (PXRD)

  

We operate this endstation at a fixed photon energy of 15116 eV (λ = 0.8202 Å) using Si(111). The default detector is a Dectris Mythen2 X series 1K. We also offer a range of devices for temperature control and gas flow.

We now offer a mail-in access option for powder diffraction!

PXRD sample preparation and mounting

Our standard method of mounting powder samples is within Kapton capillaries, sealed on both ends. Capillaries are sourced from Cole Parmer. We have several inner diameters available on site: 0.30 mm, 0.50 mm, 0.63 mm and 0.81 mm. We can supply capillaries and help with loading. The choice of capillary diameter is dependent on the X-ray absorption of the sample. Samples with a large fraction of high Z elements may produce the best data within small diameter capillaries. This APS website provides useful guidelines. We use the free program MAC 3.0 for calculating sample absorption at the beamline. It can be downloaded here.

IMPORTANT: The capillary should be no more than 25 mm long, no less than 10 mm long, and with a plug of material at least 4 mm long (preferably more). The capillary should be sealed on both ends with wax or superglue, even if the compound is not air sensitive. Take care not to form a bead of glue at the end which is wider than the capillary, or it may not be possible to fit it in the magnetic stub holder. Grind your samples well before loading, as large grains will reduce the quality of the data.

   

The sealed capillary is then mounted on a reusable magnetic stub with a small amount of wax or modelling clay. The magnetic stubs are from Mitigen, Goniometer Base Type B3S-R, GB-B3S-R-40. We will provide the stubs for users. The capillaries are typically measured while spinning at a rate of about 3.5 rotations per second.

For best results, we encourage users to,

  1. Load your samples in capillaries ahead of the beamtime (see instructions above) if the samples are in powder form.
  2. Create a priority list ahead of your scheduled beamtime: Determine which samples and which measurements are the most important. We want to ensure that your most important measurements get done in case there are unexpected problems. Typical PXRD samples can be measured at a rate of about 3 samples per hour.
  3. Use a very simple naming convention for your samples (A1, A2, A3, B1, B2, C1, etc.). This makes it much easier for staff who receive hundreds of samples a week.

PXRD data format and how to view your data

When you receive your data we will typically include three types of files:

  • Files with the extension .xye are the PXRD data. The format is essentially that of TOPAS data with no header. The first column is 2θ, the second column is intensity in counts/s, and the third column is error. We use the free program GSAS-II for most PXRD data workup. These files open in GSAS-II (import, powder data, guess format from file). When it asks for an instrument parameter file, load in the BXDS_Huber.instrprm file available below for dowload. Now the data file should open. By refining the data for the calibration standard LaB6, using the .cif file for LaB6 available for dowload below, you can create, save, and apply your own instrument parameter file to the data. PyMCA is a free program also useful for quickly viewing the patterns.
  • The files with no extension are the individual frames from the scan, and can be viewed with PyMCA. These frames get merged together to form the .xye files. Typically users will not need these, but they can sometimes be useful.
  • Lastly, there are files that end in _spec. These contain additional information collected during the scans, such as ion chamber readings and the ring current for each point in the scan.

 

Click here to download a collection of helpful PXRD files:

  • A GSAS-II instrument parameter file specific for the Huber endstation (updatedJune 9, 2022)
  • Example of a .xye file for LaB6
  • Example of the MAC program entried for LaB6
  • .cif file for LaB6
  • Information from NIST on the LaB6 calibration sample (NIST 660b) 
  • A step-by-step tutorial for how to refine LaB6 in GSAS-II

 

 

SAXS/WAXS

    

Small and/or wide angle X-ray scattering measurements generally use our Huber 4 circle diffractometer as the sample holder. Measurements are made at a fixed energy of 15116 eV (λ = 0.8202 Å), and can be performed in grazing incidence or transmission geometry.

We can also operate SAXS for transmission samples at 10.5 keV, with a grazing incidence mode under development. SAXS is also in development on the undulator beamline, which can accommodate a 4 meter long flight tube and variable photon energy.

Multi-sample holders are available for high-throughput transmission and grazing incidence measurements (8 - 10 samples per hour). The default detector is a Rayonix MX300, with 300 mm × 300 mm active area, typically operated in 2×2 binning mode (73.242 μm pixel size). The maximum detector distance is 2400 mm and the minimum is 175 mm.

We can measure powders, thin films. liquids, pharmaceuticles, nanoparticles in solution or on surfaces, micelles... the list goes on! For liquids, we generally need minimum 40 uL for the measurment, at concentrations of 10 mmol, or about 1 to 10 mg/mL. Liquid samples are measured in glass or kapton capillaries. We can load up 10 capillaries at a time on our motorized sample holder. The actual data acquisition time is about 5 minutes. We supply silver behenate for the detector calibration, and we have glassy carbon as an intensity standard.

For best results, we encourage users to,

  1. Let us know in advance the q (Å-1) and d (nm) range, and angles of incidence, you are most interested in. This will minimize setup time and we can optimize the setup for your specific problem. Our currently available q and d range is tabulated above.
  2. Create a priority list: Determine which samples and which measurements are the most important. We want to ensure that your most important measurements get done in case there are unexpected problems. If the samples are all about the same size, we can measure about 8 samples per hour with the multi-sample stage. Also, switching from WAXS to SAXS or vice versa involves a few hours of setup and tuning, so samples should be grouped by technique.
  3. Use a very simple naming convention for your samples (A1, A2, A3, B1, B2, C1, etc.). This makes it much easier for staff who receive hundreds of samples a week.

SAXS/WAXS data format and how to view your data

Data/images from the Rayonix detector are in the .tif file format. The files are 33 Mb each, so take care to manage the amount of unnecessary images collected. For example, avoid collecting images during initial alignment scans or delete them. The free program ImageJ is installed at the beamline for a quick visual check of the image quality. We use the free program GSAS-II for some SAXS/WAXS data workup. The .tif files open in GSAS-II (import, image, from TIF image file). Now the data file should open. By refining the data for the calibration standard such as silver behenate or LaB6, you can calibrate the detector, and then apply the calibration to your data to perform azimuthal integrations in units of q. GSAS-II has excellent turtorials which fully describe these steps (help, tutorials, browse tutorial on web, calibration of an area detector, and integration of area detector data). The free Matlab program GIXSGUI is also popular for more advanced data workup,

 

In-situ rapid thermal annealing (IBM endstation)

  

This highly specialized endstation can perform simultaneous in-situ diffraction, four point probe resistivity measurements, and surface roughness measurements on thin films during rapid annealing, up to 1100°C. We currently offer a choice of two energies, 8.0 keV with Si(111), or 15.1 keV with Si(311).

 

Our detectors

Mythen

Dectris Mythen2 X series 1K with DCS4. This Si pixel detector has an active area of 8 mm × 64 mm, consisting of a linear strip of 1280 pixels, 50 µm wide, with 1000 μm sensor thickness. It has a linear response up to 700,000 counts/s. It has almost no dark noise and has an acquisition rate up to 1000 Hz. This the default detector for PXRD measurements at the LE beamline.

Rayonix

Rayonix MX300. The CCD area is 300 mm × 300 mm with 8192 × 8192 pixels (36.621 μm × 36.621 μm pixels). We typically operate in 2×2 binning (4096 × 4096), or 73.242 μm × 73.242 μm pixel size with 1 s acquisition rate. The acquisition rate increases to 0.3 s with 4×4 binning. The maximum counts per pixel is 216 = 65536. This is our main SAXS/WAXS detector.

Scintillator

FMB Oxford C30NA50B, with Oxford C400 detector electronics. This detector is excellent for measuring weak signals, but has a low dynamic range of about 4 orders of magnitude

Photodiode

We have a selection of photodiodes available at the beamline. The output can be monitored using Keithley 6485 picoammeters or Stanford Research SR570 current preamplifiers. The good sensitivity and high dynamic range of 6 - 8 orders of magnitude is well suited to single crystal and reflectivity measurements. We also use them in active beamstops for SAXS/WAXS.

Hitachi Vortex

X-ray fluorescence detector, just arrived and being commissioned.