X-ray Monochromators


Home > Photonic Materials > X-Ray Monochromators

A monochromating crystal behaves in X-ray spectrometry as does a diffraction grating in optics. When rotated with respect to the incident beam it will diffract the spectral component in accordance with Bragg's Law. The most important characteristic of a monochromating crystal is the double atomic spacing 2d, which is the largest wavelength which can be diffracted. The St Gobain Crystals & Detector's range of synthetic & naturally occurring monochromating crystals offers the widest possible variety of 2d spacing.

Our monochromating crystals are supplied as flat (unmounted or mounted on holders) for XRF spectrometers etc, or curved onto a holder to allow focusing for instruments such as microprobes, scanning electron microscopes etc.

Basic Principle of Monochromating Crystals

The spectral analysis of X-Rays emitted by a sample after irradiation is both a powerful qualitative and quantitative analytical technique. It is based on the following phenomenon: an atom relaxes after excitation by emitting characteristic X-Ray radiations, which reveal the identity of the emitting species.

A spectrometer consists of :

Monochromating Crystals

NameOrientation   2D Spacing
(Angstrom)   
Useful Range
(Angstrom)   
LiF 200 4.027 0.351 - 3.840
220 2.848 0.248 - 2.720
420 1.801 0.157 - 1.720
Quartz    10 - 10 8.514 0.742 - 8.340
10 - 11 6.684 0.583 - 6.380
InSb 111 7.48 0.652 - 7.230
Si 111 6.271 0.547 - 5.980
220 3.840 0.335 - 3.660
Ge 111 6.532 0.570 - 6.230
220 4.000 0.349 - 3.820
PET 002 8.740 0.762 - 8.340
EDDT 200 8.808 0.768 - 8.400
ADP 101 10.648 0.654 - 7.160
Beryl 10 - 10 15.950 1.390 - 15.220
TIAP 001 25.900 2.260 - 24.700
RbAP 001 26.120 2.280 - 24.920
KAP 001 26.640 2.320 - 25.410

Flat plates

Curved plates

- The Johann geometry

- The Johansson geometry

Johansson Curvature Johansson Curvature