Xray Crystallography Research Paper Example | Topics and Well Written Essays - 1250 words

Xray Crystallography - Research Paper Example With the advancement in technology and discovery of X-rays, crystallographers found a powerful source of obtaining complete information about any type of crystal. With a wavelength of the order of 1010, comparable to that of the diameter of an atom, X-rays have the ability to penetrate into the crystal and get diffracted by atom, ions or molecules in their way. With the discovery of this technique in 1940s, the scientists used the specific wave-particle nature of X-rays to determine the arrangement of the constituent specie in a crystal. Crystal and its pattern: Crystal is a three dimensional pattern obtained by the repetition of unit cell, the smallest possible, arranged volume of any crystalline solid. In crystals, the atoms, ions or molecule (the constituent species) are held into their orderly arranged positions by inter atomic, inter ionic or inter molecular forces respectively. The scientists were searching for a way to determine the pattern of their arrangement. Once the patte rn could be known, all the other information about the substance was easy to get. Crystals were not studied, deeply, until the 17th century. â€Å"Crystal symmetry was first investigated experimentally by Nicolas Steno (1669), who showed that the angles between the faces are the same in every exemplar of a particular type of crystal, and by Rene Just Hauy (1784), who discovered that every face of a crystal can be described by simple stacking patterns of blocks of the same shape and size.† (â€Å"X-ray Crystallography. Wikipedia†)... Only X-rays have the ability to penetrate into a crystal and determine the three dimensional pattern by getting diffracted by the constituent particles. The technique of X-ray Crystallography: X-ray Crystallography uses a focused X-ray beam to reveal the structure of a crystal. X-rays strike the particles in a crystal and spread into many specific directions. Censors present around the crystal then cense the angle of diffraction and the strength of the beam reaching them. The pattern produced by the diffraction of X-rays through the closely spaced lattice of atoms is recorded and analyzed to reveal the structure of the crystal. The very basic fact exploited by this technique is that X-rays are diffracted by crystals. With the invention of this technique, Crystallography was completely revolutionized and improved. X-rays and their production: â€Å"X-rays are electromagnetic radiation with wavelengths between about 0.02 A and 100 A (1A = 10-10meters).† (Nelson) They are produce d when electrons from a cathode strike the electrons in the inner shells of transition elements. As these electrons are hit, the energy from moving electrons is transferred to them. Thus, these electrons excite and during de-excitation, these electrons emit radiations of high energy, whose wavelength lies in the invisible region of electromagnetic spectrum. These high energy, less wavelength possessing waves can penetrate into most of the crystals. X-ray Diffraction and Bragg’s law: As X-rays hit a row of particles in a crystal, they are diffracted. Actually, the diffraction is the interaction of separate waves of X-ray beam. It can be considered as the reflection of X-ray beam from the row of constituent particles that are arranged in a crystal. There are