Huber G670 - Powder Diffraction Camera
Following the success of the HUBER G670 a new version has been released.
The new version comes with automatic beam adjustment and in two different versions: the 670-180 and the G670-360.
The wet film technique of the old HUBER Guinier Camera 621 has been replaced by an up-to-date detection system involving a modern imaging plate in the first version of the G670. For a long while digital X-ray powder diffraction intensity data have been achieved by the use of a single channel step scan scintillation detector. Now, these data are available within a couple of minutes instead of hours, because of the time multiplex effect of the position sensitive imaging plate method.
The camera housing contains the complete read out unit including laser scanner, signal preamplifier and erasure lamp.
This instrument combines the high resolution of the old wet film technique with the extreme fast sensitivity of the imaging plate process giving the digital intensity data of the Guinier powder diffractogram, ready for Rietveld analysis. That imaging plate method supersedes even the position sensitive proportional detector technique. This is because of the relative small focal circle diameter of 180 mm, which cannot be met by a proportional PSD.
The 670 package includes the hard- and software required for the control of the data collection. A maximum of 20001 data points per scan can be stored into most of the common data file formats, compatible to any crystallographic evaluation software.
Unterschied G670-180 und G670-360
The effective resolution of an x-ray powder measurement is determined by the following factors:
- sample powder
- monochromator
- x-ray wavelength
- quality of x-ray source
- goniometer
- detector
For both versions of the HUBER G670 the resolution of the detector itself is higher than the signal from the sample which reaches the detector.
For this reason, increasing the diameter of the G670-360 increases the resolution for harder x-rays (for example Ag or Mo), whereas for softer x-rays (for example Cu or Co) the G670-180 is the better choice.
What is an image plate?
A flexible mounting foil made of polyester is coated with a homogenous powder
consisting of crystallites (particle size approx. 0.005mm) of a luminescent storage
material, namely photo-stimulatable phosphor consisting of bariumflourobromide
with trace amounts of Europium with a valence of 2 which acts as a luminescence
centre (BaFBr:Eu2+).
The image storage foil is positioned in the Guinier camera 670 with the sensitive
side facing inward precisely on the focal circle with a radius of 90mm. It is exposed
in the same way as the previously used wet film. After this, the image plate is
scanned by a vertical linear red diode laser beam within approximately 5 seconds.
The thus resulting blue photostimulated liminescence (PSL) emanating from the
areas subject to X-ray exposure is amplified during the scanning process by a
photomultiplier and then registered. This initially analog signal is then converted
into digital number counts by a 16-bit A/D converter.
By means of a white halogen lamp it is possible to delete the registered image
structure within 10 seconds. After this process the Guinier camera is ready for
the next image.
Huber G670
Following the success of the HUBER G670 a new version has been released.
The new version comes with automatic beam adjustment and in two different versions: the 670-180 and the G670-360.
The wet film technique of the old HUBER Guinier Camera 621 has been replaced by an up-to-date detection system involving a modern imaging plate in the first version of the G670. For a long while digital X-ray powder diffraction intensity data have been achieved by the use of a single channel step scan scintillation detector. Now, these data are available within a couple of minutes instead of hours, because of the time multiplex effect of the position sensitive imaging plate method.
The camera housing contains the complete read out unit including laser scanner, signal preamplifier and erasure lamp.
This instrument combines the high resolution of the old wet film technique with the extreme fast sensitivity of the imaging plate process giving the digital intensity data of the Guinier powder diffractogram, ready for Rietveld analysis. That imaging plate method supersedes even the position sensitive proportional detector technique. This is because of the relative small focal circle diameter of 180 mm, which cannot be met by a proportional PSD.
The 670 package includes the hard- and software required for the control of the data collection. A maximum of 20001 data points per scan can be stored into most of the common data file formats, compatible to any crystallographic evaluation software.
The Imaging Plate is a flexible image sensor in which bunches of very small crystals (grain size: about 0.005 mm) of photostimulable phosphor of barium fluorobromide containing a trace amount of bivalent europium as a luminescence center, formulated as BaFBr: Eu2+, are uniformly coated on a polyester support film.
G670-180 versus G670-360
The effective resolution of an x-ray powder measurement is determined by the following factors:
- sample powder
- monochromator
- x-ray wavelength
- quality of x-ray source
- goniometer
- detector
For both versions of the HUBER G670 the resolution of the detector itself is higher than the signal from the sample which reaches the detector.
For this reason, increasing the diameter of the G670-360 increases the resolution for harder x-rays (for example Ag or Mo), whereas for softer x-rays (for example Cu or Co) the G670-180 is the better choice.
What is an image plate?
A flexible mounting foil made of polyester is coated with a homogenous powder
consisting of crystallites (particle size approx. 0.005mm) of a luminescent storage
material, namely photo-stimulatable phosphor consisting of bariumflourobromide
with trace amounts of Europium with a valence of 2 which acts as a luminescence
centre (BaFBr:Eu2+).
The image storage foil is positioned in the Guinier camera 670 with the sensitive
side facing inward precisely on the focal circle with a radius of 90mm. It is exposed
in the same way as the previously used wet film. After this, the image plate is
scanned by a vertical linear red diode laser beam within approximately 5 seconds.
The thus resulting blue photostimulated liminescence (PSL) emanating from the
areas subject to X-ray exposure is amplified during the scanning process by a
photomultiplier and then registered. This initially analog signal is then converted
into digital number counts by a 16-bit A/D converter.
By means of a white halogen lamp it is possible to delete the registered image
structure within 10 seconds. After this process the Guinier camera is ready for
the next image.