ABSTRACT
X-rays are short wavelength radiations. Firstly, the general characteristics of X-rays are recalled. Then, the apparatus for the preparation of X-rays is described. It is a kind of Coolidge's tube. It contains one filament F of tungsten at incandescence emitting electrons and an anticathode. The electrons strike the anticathode at a great speed in a perfect vacuum. There is, then, emission of X-rays. From the analytic standpoint, it is convenient to distinguish the spectrography X emission, the absorptiometry of X-rays and the fluorometry of X-rays. Spectra X are diagrams of intensities of the peaks as a function of the wavelengths at which they appear. They are constituted by a continuous part and by a ray spectrum superimposed on the preceding part. Rays are characteristic of the elements of the target in some conditions. Concerning the absorptiometry of X-rays, a beam of X-rays loses a part of its intensity when it is passed through a thin layer of matter. The losses of intensity by absorption obey Beer-Lambert's law. The chapter also contains some comments concerning X-ray fluorescence and the diffraction X.
