Grating plane

Figure 3.5 Various orders of diffraction tfom a plane reflection grating G R indicates the red end of the spectrum V indicates the violet end of the spectrum the central number is the order of diffraction...

Fig. 5. Uniform plane wave grating where (a) is the recording, and (b) the readout.

The diffracted amphtude from illuminating such a grating with a unit plane wave normal to the surface is easily calculated again by resolving equation 9 into complex exponentials (as in eq. 10) where is the mUi Bessel function. 

Sohd-state multi-element detector arrays in the focal planes of simple grating monochromators can simultaneously monitor several absorption features. These devices were first used for uv—vis spectroscopy. Infrared coverage is limited (see Table 3), but research continues to extend the response to longer wavelengths. Less expensive nir array detectors have been appHed to on-line process instmmentation (125) (see Photodetectors). 

Figure 1 Plane wave scattering from two consecutive iines of a one-dimensionai diffraction grating. The wave scatters in-phase when the path difference (the difference in iength of the two dotted sections) equais an integrai number of waveiengths.

Figura 3 Grating spectrometers commonly used for ICP-OES (a) monochromator, in which wavelength is scanned by rotating the grating while using a singie photomultiplier tube (PMT) detector (b) polychromator, in which each photomultiplier observes emission from a different wavelength (40 or more exit slits and PMTs can be arranged along the focal plane) and (c) spectrally segmented diode-array spectrometer.

Gitter-ebene, /. (Cryst.) lattice plane, -elek-tron, n. lattice electron, -energie,/. (Cryst.) lattice energy, -farbe, /. grating color. 

As one may infer from the quotation, W. L. Bragg realized that a crystal can act as an x-ray grating made up of equidistant parallel planes (Bragg planes) of atoms or ions from which unmodified scattering of x-rays can occur in such fashion that the waves from different planes are in phase and reinforce each other. When this happens, the x-rays are said to undergo Bragg reflection by the crystal and a diffraction pattern results. 

This section refers to classically-ruled plane diffraction gratings where the grooves have a blazed profile as illustrated in Fig. 2a. 

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