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Incident Beam Part consists of X-ray Tube and Incident Beam Optics.
To see detailed overview, please click on items listed on the left.
High Resolution
Incident Beam Optics
Medium Resolution
Incident Beam Optics
X-ray Tube
Ceramic diffraction x-ray tube
Main Properties
| Anode Material | Wavelength Ka1 (Å) | Wavelength Ka2 (Å) | Wavelength Ka (Å) |
| Cu | 1.54056 | 1.54439 | 1.54184 |
| Focus | Focus Type | Focus Dimensions | |
| Line | LFF (Long Fine Focus) | 12 mm X 0.4 mm | |
| Be window diameter | Be window thickness | Working Power | Standby Power |
| 14 mm | 300 mm | 45 kV / 40 mA | 30 kV / 20 mA |
Beam Attenuators & Filters
Beam attenuator is an absorber which is placed in the x-ray beam to reduce its intensity by a specific factor.
Specific beam attenuators are designed for use with x-ray mirrors and hybrid monochromators.
Attenuation Factors for Cu Ka radiation
| Copper foil (0.1 mm) | Combined Copper (0.2 mm) / Nickel (0.02 mm) |
| ~ 100 | ~ 10,000 |
Automatic Beam Attenuator contains a Ni foil that can be set to be switched in and out of the x-ray beam either at a fixed angle or at a fixed intensity. Operation is controlled by the Data Collector software.
Automatic Beam Attenuator Operating Modes
| Mode | Application |
| Do not switch (Activated/Deactivated) | Beam attenuator stays either inserted into the x-ray beam path or removed over a whole angular range and for the full measuring time. |
| At pre-set intensity | Beam attenuator is inserted into the beam when the specified count rate ("activate" level) is reached, and/or is removed from the beam when the count rate drops below another specified value ("deactivate" level). |
| At pre-set angle | Beam attenuator is inserted into the beam when diffractometer position on th scan axis is inside the specified interval. The interval is given by the activate and deactivate angles. |
Beta-filter
| Tube Anode | Beta-filter | Thickness (mm) | Kb intensity reduction (%) | Ka intensity reduction (%) |
| Cu | Ni | 20 | 99 | 58 |
Fixed Divergence Slits
Divergence slits are fitted in the incident beam path to control the equatorial divergence of the incident beam.
Four fixed divergence slits marked 1/2o, 1/4o, 1/16o, and 1/32o are used in X'Pert diffractometer. Fixed divergence slits must be inserted into the slot for fixed divergence slits on the PreFIX module.
The length of the area on the sample that is irradiated by the incident beam is dependent on the divergence of the x-ray beam and the position of the sample with respect to the beam. It can be calculated as follows:
L - irradiated length of
the sample,
R - radius of the goniometer (R = 320mm),
d - divergence angle as is engraved on
the fixed divergence slit,
w - angle between incident beam and the
sample surface.
Incident Beam Masks
Beam masks are fitted in the incident beam path to control the axial width of the incident beam, defining the amount (width) of the sample that is irradiated by the incident x-ray beam.
The size of the beam mask opening must be such that the incident x-ray beam is completely accepted by the sample during the complete measurement.
The total width of the area on the sample irradiated by the incident beam is dependent on the size of the x-ray beam and the position of the sample with respect to the beam.
X-ray Mirror
Graded multilayer parabolic x-ray mirror is a special kind of beam conditioner, which is able to convert the divergent x-ray beam from a line focus tube to an intense monochromatic quasi-parallel beam. X-ray mirror provided with X'Pert diffractometer is designed to diffract characteristic Ka radiation. Kb radiation is suppressed to a level below 0.5% of its original level.
The x-ray mirror accepts ~0.8o of the x-ray beam from the line focus of the x-ray tube. The quasi-parallel beam diffracted by the mirror has a small horizontal (equatorial) divergence (< 0.05o). The beam from the x-ray mirror is ~1.2mm high and ~20mm wide. The beam emitted from the x-ray mirror is offset relative to the direct beam from the x-ray tube. This offset angle is referred to as the "mirror offset". The data collector software will always apply an offset whenever the x-ray mirror is present in the incident beam path.
Slit size and the irradiated length
| Slit Marking | Beam height (mm) | Irradiated length (mm) |
| 1/2o | 1.2 | 0.12 + 1.2 / sin(w) |
| 1/4o | 0.6 | 0.12 + 0.6 / sin(w) |
| 1/8o | 0.3 | 0.12 +0.3 / sin(w) |
| 1/16o | 0.15 | 0.12 + 0.15 / sin(w) |
w - angle between the incident beam and the sample surface.
X-ray Lens
X-ray Lens (or polycapillary optics) consists of a few million glass capillaries (~ 5 mm in diameter) combined together into a round crosssection and bent in parabolic shape. X-rays are traveling through the capillaries due to total reflection.
Hybrid monochromator will offset the x-ray beam. The hybrid monochromator passes slightly broader spectral range than traditional four-crystal monochromator and therefore delivers a much more intense parallel beam of Ka1 radiation. Ka2 component is suppressed to a level below 0.1%. It may become visible during reciprocal space mapping with large dynamic range.
X-ray Lab owns hybrid monochromator 4X, consisting of a combination of an x-ray mirror and a 2-crystal Ge(220) 4-bounce monochromator. The acceptance angle from line focus of the x-ray tube is 0.8o. The height of the x-ray beam emerging from the hybrid monochromator is 1.2 mm.
Slit size and the irradiated length
| Slit Marking | Beam height (mm) | Irradiated length (mm) |
| 1/2o | 1.2 | 1.2 / sin(w) |
| 1/4o | 0.6 | 0.6 / sin(w) |
| 1/8o | 0.3 | 0.3 / sin(w) |
| 1/16o | 0.15 | 0.18 / sin(w) |
w - angle between the incident beam and the sample surface.
Programmable Divergence Slits
Programmable Divergence Slit PreFIX module is fitted in the incident beam path to control the equatorial divergence of the incident beam.
The divergence slit is software controlled to operate in one of two modes:
Fixed divergence slit mode. It provides a defined divergence of 4o, 2o, 1o, 1/2o, 1/4o, 1/8o, 1/16o, or 1/32o.
Automatic divergence slit mode. It provides a defined irradiated length of 20 to 0.5 mm in 0.1 mm steps. The divergence is changing automatically as a function of the angle between the incident beam and the sample surface w.
The relative intensities measured with PDS in automatic mode will differ considerably from those measured in fixed mode. The results can be compared using the following formula:
F = conversion factor
IFDS = intensity
measured in fixed slit mode
IADS = intensity
measured in automatic slit mode
R = goniometer radius
d = divergence angle in fixed slit mode
La = irradiated
sample length in automatic slit mode
w = angle between incident beam and sample
surface
Soller Slits
Soller Slits are used together with the programmable divergence slit (PDS) to control axial divergence of the x-ray beam. Soller slits with the shutter lever must be inserted into PDS in order to activate the shutter safety switch.
Using soller slits improves the peak shape and the resolution in 2q-type scans, particularly at low scattering angles.