Small/Wide Angle X-Ray Scattering (SAXS/WAXS)

Small/Wide Angle X-Ray Scattering (SAXS/WAXS) System (Rigaku S-MAX 3000)

Contact: Dmitri Barbash

 

Important Features

       General Description

  • Small-Angle X-ray Scattering (SAXS) is a technique where the elastic scattering of X-rays by a sample which has inhomogeneities in the nanometer range, is recorded at very low angles (typically 0.1 - 10°)
  • The studied samples can be solid or liquid and they can contain solid, liquid or gaseous nanodomains of the same or another material
  • SAXS provides information about particle size distribution, particles/domains shape and orientation, shape and size of macromolecules, characteristic distances of partially ordered materials, pore sizes, and other data
  • Accurate, non-destructive technique that most often requires only minimum sample preparation
  • At Drexel SAXS is complemented on the same setup by Wide-Angle X-ray Scattering (WAXS) as the physical principle of both techniques is the same - coherent scattering from fluctuations in the electron density of the sample
  • WAXS provides data of long-range periodicity of materials with d-spacing of 0.1 – 1 nm (crystal structures of most organic and inorganic materials)

       SAXS/WAXS System Parameters

Source to Optics distance                                              55 mm
Source to Sample distance                                            1475 mm
Source to Detector distance                                          3000 mm
Beamstop Diameter (SAXS)                                          4 mm
Sample to Detector distance (SAXS)                            1525 mm
Sample to Image Plate distance (WAXS)                      manually variable from 30 mm to ca 200 mm
SAXS ranges:
Q min                                                                             0.0067 Å-1
d max                                                                             910 Å
Q max (detector 120 mm)                                              0.16 Å-1
d min (detector 120 mm)                                                39 Å
WAXS wide angle range at 30 mm                              2Theta_max is 74 deg, 2Theta_min is 9 deg
WAXS wide angle range at 200 mm                            2Theta_max is 27 deg, 2Theta_min is 1.5 deg

SAXS Data Analysis Software

Matlab-based Graphical User Interface (GUI)
Background subtraction
Image centering
Polar coordinate transform
Principal axis determination and elliptical overlay for anisotropic materials
Unwrapping to chi vs. k Cartesian coordinate system
Integration over chi, k
Data reduction (background subtraction, intensity normalization) using file references setup at the time of data acquisition

 X-ray source

MicroMax-002+ Microfocus Sealed Tube X-ray Source with SAXS Optic
Factory integrated Confocal Max-FluxTM (CMF) Optic designed for SAXS
X-ray wavelength: CuKα = 1.54 Å 
• Divergence: 4.8 mrad
Focal spot: 20 x 20 microns
Power: 40 W

SAXS 3-Pinhole Camera System

Filter box with pneumatic actuation
Three (3) pinhole housings with micrometer alignment
Two pinholes for beam definition: 400 μm and 200 μm
One guard pinhole before sample: 700 μm
Photodiode beam stop to provide transmission factor; includes current/voltage amplifier
Manual slit positioning from outside of system vacuum
• Ag Behenate q calibration standard
• Calibrated glassy carbon standard for absolute intensity calibration
• Segmented beam pipe allows the detector to be moved closer to the sample

Universal Large Sample Chamber and Scanning Stage

• Inner dimensions: 345mm (W) x 390mm (D) x 380mm (H)
• X-Y Scanning Stage and Automated Sample Changer
• Horizontal and Vertical scanning capability used for precise two dimensional sample mapping. A two dimensional array of 42 or more samples may be measured automatically.
• Fully programmable with LabVIEW drivers
• Automated software script provides sample alignment, transmission and automatic sample position advance
• 10 micron resolution of the stage movement 
• >50mm (+/- 25mm) translation range
• Sample holder with 42 positions for samples or a capillaries
 

Linkam High Temperature Control Stage

Temperature control from -50 to 300° C with +/- 0.1°C precision using a combination of fluid coolant and integral heater
LN2 pump for rapid cooling rates low temperature control
Operates in vacuum
• Works with solid samples
1 mm & 2 mm Sandwich sample cells: Custom Design by Linkam to Rigaku Specifications; Mica and Kapton Windows and Viton and Kalrez o-rings available

Two Dimensional Multiwire X-ray Area Detector

• Gabriel design Multiwire, gas-filled proportional type detector
• True 120 mm diameter active area
• ca 200 micron resolution
• 1x105 maximum counts per second
• Matlab analysis package
• Low-absorption Carbon Fiber window
Fe55 source for detector efficiency calibration
• Sub-millisecond time stamping for individual events
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