The Röntgen Radiation and its application in studies of ... - Mansic

kinetic energy of the electron is transformed totally or partially, into a photon of
X-ray, with its frequency ν given by Einstein’s equation:
2 2 ( v − v ) = ⋅ϑ
⎛ m ⎞
∆E = ⎜ ⎟ ⋅ 1 2 h
⎝ 2 ⎠
b. The characteristic spectrum. Another type of interaction of the accelerated
electron with an atom could result in the expulsion of an electron from the
interior electronic orbits of the target atom and then the atom remains in an
excited, ionized state. In order to come back to the normal state the jump of one
electron from higher orbital is needed. Excess of energy is emitted as a photon of X-ray
whit constant value of the wavelength.
X-ray diffraction is used for:
• Measuring the average spacing between crystallographic plains
• Determination of the orientation of a single crystal or grain
• Quantitative and qualitative phase analysis
• Finding the crystal structure of an unknown material
• Measuring the size, shape and internal stress of small crystalline regions.
Properties of X-rays
The importance of X-ray in diffraction studies is generation when high-energy
electrons impinge a metal target. The most useful metal for anode construction is
iron, copper, cobalt and molybdenum. At a sufficiently high voltage the X-ray
emits a beam, which is shown in Figure 4 [5]. It consists of two parts, a broad
band of continuously varying wavelengths with a broad energy maximum in the
neighborhood of 0,5 Å and a characteristic spectrum superposed on it combined
from two series: Kα and Kβ. The Kα line is always 2/3 more intense than Kβ.
Scheme of Kα and Kβ emission is shown in Figure 5. Actually the Kα line is itself a
doublet with components Kα1 and Kα2 separated by such a small interval that is
most X-ray diffraction patterns they are resolved only at higher range of 2θ.
Figure 4. Intensity curve for X-rays from a molybdenum target operated at 35kV
Physics of Advanced Materials Winter School 2008 6