Generation of X-Rays

Generation of X-Rays :  When metals, like copper, molybdenum, tungsten, etc., are 

bombarded directly with a stream of high energy electrons or radioactive particles, X-rays  

(wavelengths of order 0.1-100Å) are emitted because of the transitions involving K-Shell and 

L-Shell electrons. This can be simply expressed as follows: 

A cathode in the form of a metal wire when  electrically heated gives off electrons. If a 

positive voltage, in the form of an anode (target comprised of the metals mentioned above), is 

placed near these electrons, the electrons are accelerated toward the anode. Upon striking the 

anode, the electrons transfer their energy to the metallic surface, which then gives off X-ray 

radiation. This is referred as primary X-rays.  

The following is the schematic diagram for the process:

Note:  The wavelength of the emitted X-ray is characteristic of the element being 

bombarded. Hence with some modifications this process can be used as a tool for 

qualitative and quantitative elemental analysis by measuring the wavelength and emission 

intensity of the X-rays respectively. This forms the basis for Electron Probe Microanalysis!