圣戈班晶体为此类光谱分析提供两个关键组件:
单色晶体用于分散样品发射光束的各种光谱分量。 探测器用于测量单色器选出的光谱线强度。
可提供以下两种形状的单色晶体:
平面晶体可提供非安装到托架或安装到托架两种。 圣戈班可提供标准型或定制型托架。用于微探针、扫描电子显微镜、同步加速器、XFEL、等离子体物理等仪器的弯曲晶体始终以定制托架方式供货。
可以考虑两种主要聚焦配置类型:
约翰几何(半聚焦)
通过以下两种方法其中之一获得薄板:
然后将薄板弯曲成圆柱形,并粘合到近似聚焦的曲面托架上。
约翰逊几何(精确聚焦几何)
考虑理论上可获得完美聚焦的两种不同类型约翰逊配置:
薄板要么弯曲成圆柱形,粘合到曲面托架上并对一面进行机械加工(单机械加工约翰逊),要么两面进行机械加工,然后粘合到曲面托架上(双机械加工约翰逊)。
圣戈班晶体将根据晶体类型选择最合适的技术,从而获得罗兰圆的尺寸和半径。
其他类型的曲率可根据要求进行研究。可提供以下设计:
生产能力与晶体性质、尺寸以及曲率半径密切相关。
Monochromating crystals
A monochromating crystal behaves in X-ray spectrometry as does a diffraction grating in optics. When rotated with respect to the incident polychromatic beam (see figure), it will diffract the spectral component along with direction to satisfy Bragg’s law, namely: 2d sin θ = n λ where integer n refers to the diffraction order.
Hence, the most important characteristic of a monochromating crystal is the double atomic spacing 2d, which gives the largest wavelength to be diffracted.
The range of monochromators supplied can be found in Monochromator Crystal Properties along with the usual surface finish, within our control means, to the best intensity-resolution compromise. The optimum depends on each specific case and strongly reflects the nature of the set-up.
An X-ray spectrometer basically consists of:
An excitation source which may be either a primary X radiation, in which case one refers to X-ray fluorescence spectrometry. Or an electron beam, inducing a so-called direct emission, used in microprobes and scanning electron microscopes.
A monochromating crystal which is used to disperse the various spectral components of the incident beam.
A detector in order to measure the intensity of the various spectral lines as singled out by the monochromator.
The detector offered by Saint-Gobain Crystals combines a Nal(TI) or Lanthanum Bromide scintillator directly coupled to a photomultiplier with a low absorbing MIB or beryllium entrance window.
Scroll right for additional crystals → | |||||||||||||||||||||
Crystal | Lithium fluoride | Quartz | Indium Antimonide | Silicon | Germanium | Pentaerythritol PET | Ammonium Dihydrogen Phosphate ADP | Beryl | Acid Phthalates | Crystal | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Thallium TIAP | Rubidium RbAP | Potassium KAP | Cesium CsAP | ||||||||||||||||||
Chemical Formula |
LiF | SiO2 | InSb | Si | Ge | C(CH2OH2) | NH4H2PO4 | 3BeO,Al2O36SiO2 | CO2HC6H4CO2TI | CO2HC6H4CO2Rb | CO2HC6H4CO2K | CO2HC6H4CO2Cs | Chemical formula | ||||||||
Crystal system | Cubic | Hexagonal | Cubic | Cubic | Cubic | Quadratic | Quadratic | Hexagonal | Orthorhombic | Orthorhombic | Orthorhombic | Orthorhombic | Crystal System | ||||||||
Parameters |
|
Parameters | |||||||||||||||||||
a..................Å.... | 4.027 | 4.913 | 6.48 | 5.431 | 5.658 | 6.16 | 7.530 | 9.21 | 6.63 | 6.55 | 6.46 | 6.580 | a..................Å.... | ||||||||
b..................Å.... | 4.913 | 6.16 | 7.530 | 9.21 | 10.54 | 10.02 | 9.61 | 10.752 | b..................Å.... | ||||||||||||
c..................Å.... | 5.405 | 8.74 | 7.542 | 9.17 | 12.95 | 13.06 | 13.33 | 12.825 | c..................Å.... | ||||||||||||
ß........................ | ß........................ | ||||||||||||||||||||
Reflecting planes orientations | (200) | (220) | (420) | (1011) | (1010) | (111) | (111) | (220) | (111) | (220) | (002) | (101) | (1010) | (001) | (001) | (001) | (001) | Reflecting planes orientations | |||
2d in Å | 4.027 | 2.848 | 1.801 | 6.684 | 8.514 | 7.480 | 6.271 | 3.840 | 6.532 | 4.000 | 8.740 | 10.648 | 15.950 | 25.900 | 26.120 | 26.640 | 26.650 | 2d in Å | |||
Usual surface finish | Cleaved or Treated | Treated | Treated | Polished | Polished | Polished | Polished | Polished | Polished | Polished | Cleaved or Treated | Polished or Treated | Polished | Cleaved | Cleaved | Cleaved | Cleaved | Usual surface finish | |||
Reflectivity | Intense | Intense | Average | Good | Good | Intense | Intense | Average | Intense | Intense | Intense | Average | Average | Intense | Intense | Good | Good | Reflectivity | |||
Calibration elements |
Mo, Fe, Ti |
Mo, Fe | Mo | Cu | Cu | Si | Cu | Cu | Cu | Cu | Al, Si | Mg | Mg | Na, Mg | Na | Na | Na | Calibration elements | |||
Common Applications | From K to heavy elements | Heavy elements Lines splitting |
Heavy elements Lines splitting |
As Ge (111) |
As PET | Quantitative analysis of silicon | Extinction of even order spectral lines | Mg | Na and following elements | F to Al | Na to Al, up to F in emission probes | Na to Al, up to F in emission probes | Na to Al, up to F in emission probes | Common applications |