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X-ray Astronomy

This branch of physics was born in 1962 when Italian–American astronomer Riccardo Giacconi discovered a cosmic x-ray source in the form of a compact star located in the constellation of Scorpius. For this discovery Giacconi received the 2002 Nobel Prize in Physics. X-ray astronomy is a relatively new branch of astronomy dealing with the study of x-ray emission from celestial objects, such as neutron stars, pulsars, and black holes. Since the X-rays emitted by celestial objects have relatively low energies of the order of a few KeV, they cannot penetrate through the Earth’s atmosphere to reach the surface of the Earth. Thus, to study these celestial rays, detectors must be taken above the Earth’s atmosphere. Methods used to achieve this involve mounting x-ray detectors on rockets, balloons, or satellites. The x-ray detectors used for this purpose are either special charge-coupled devices (CCDs) or micro calorimeters.

X – Ray Crystallography

 X- ray crystallography is a study of crystal structures through the use of X-ray diffraction techniques. X-rays are very suitable for this purpose because their wavelength in the 0.1 Ao (~ 100KeV) to 1 Ao (~10 KeV) range is of the order of typical crystalline lattice separations. An X-ray beam striking crystalline lattice is scattered by the spatial distribution of atomic electrons and the imaged diffraction pattern provides information on the atomic or molecular structure of the crystalline sample. In 1912, Max Von Laue established the wave nature of X rays and predicted that crystals exhibit diffraction phenomena. Soon, there after William H. Bragg and William L. Bragg analyzed the crystalline structure of sodium chloride, derived the Bragg relationship and laid the foundation for X- ray crystallography.

X Ray Spectroscopy

X ray spectroscopy is an analytical technique for determination of elemental composition of solid or liquid sample in many fields Such as material science, environmental science, geology, biology and forensic science. The technique is divided into three related categories. The most common of them is the X-ray absorption spectrometry (also called as X-ray fluorescence spectrometry). The other two are X-ray photoelectron spectrometry and auger spectrometry. All three techniques rely on creation of vacancies in atomic shells of the various elements in the sample under study as well as on an analysis of the effects that accompany the creation of vacancies.


Electromagnetic radiation emitted by charged particles (usually electrons) in changing atomic energy levels.