X-ray Diffraction and Types of Mass Spectrometry

X-RAY DIFFRACTION → X-rays were first discovered by Wie Roventgen in 1895. →They have ON wavelength range of about 0.01-10nm for the purpose of chemical analysis, the most useful range is between 0.01-0.30m x-ray difpraction is a 200- destructive analysis method that reveals information about internal structure of crystalline Substances. PRINCIPLE 1- Brag's law which relates the wavelength of electromagnēlic radiation to dipyraction angle and the laltice spacing in a crystalling sample porms the basis of XRD. →In XRD, the x-raye are generated in a x- X-ray-tube which are subsequantly filtered to produce monochromatic radiation, directed Howards the sample. ← When the angle of incidence satisfies the bragg's equation, Xrays are dippracted by the crystals. The dippracted rays are then collected by the detector. the The angle at which the radiation gets dippracted from-the crystal is related to the atomic spacing in the crystals. BRAGG'S LAW:- When x-ray beam strikes a crystal surfpre at an ریا angle o' electrons constituting the atoms of a crystal surface oscillato at the same brequency as that of the incident x-ray beam and emits praction of electromagnēlic radiation while test of them Penetrates to the second layer. Again in the second layer some part of the of the radiation gets scattered while rest of them penetrates to the third layer and so on. → Every crystalline substance scatters the rays in a unique dippraction pattern and thus producing Dinger prints which is characteristic to its molecular structure The scattered rays may give constructive interference Or distructive constructive interperence of the scattered rays emerging from two dipperent places is obtained only in the Or distance between two planes is of wavelength. equal path length to the whole numbers →Basic requirements of the x-ray diffraction are:- I path length 21 Scattering centers should be spätially disturbed. When an x-ray beam strikes the crystal surface making an angle praction of the incident radiation gets scattered during to its As interazlion with located at O, P and R. AS mentioned above Path length or distance between the Hanes limin is identical and represented as 'd'. When an x-ray beam strikes the top crystal plane at O' and the other x-rays strikes the second crystal plane at 'p' path length between the parallel x-rays is equal to AP1 PC. πλ=2dsine INSTRUMENTATION:- → The main components of an x-rays dippraction instrument are:- 1- X-ray source 2. Collometer 3. Monochromater filter monochromater Ibi crystal monochromater 4- Detectors (as photographic detector by counter detector 5- Read out device. x-my beam POWDER CRYSTAL METHOD:- This method was developed by Debbye and Scherrer to Perform multicomponent analysis. →Jn this the axis method powdered specimen is mounted vertically on of cylindrical camera and the photographic film is held around the camera in the form of circular arc. →The dippracted beams bilm. are recorded traces on the Angle of incidence o equation can ban calculated from the B= 360° x 1 where 1= length bilm radius value of o be substituted in bragg's equation ROTATING CRYSTAL METHOD:- In 1919, Scheibold developed the rotating crystal method to determine the value of lattice like the unit cell. →in this method narrow monochromatic beam. of x-rays is made strike the crystal mounted perpendicular to the incident beam on a shaft. → A cylindrical film placed around it and then the crystal is rotated by means a motor. →As the crystal rotates of crystal planes at the corred Bragg's angle with the point diffraction occurs, some point makes Incident beam and at that →Diptraction pattern is recorded on the photographic plate. APPLICATIONS:- →10 determine structure of crystals. determine polymer characteristics. 70 determine the state of anneal in metals. The particle size and degree of crystanity can following x-ray techniques such angle scattering. as be determined by spot counting method and low →The cis and trans Isomers of Using X-ray dippraction. a complex can be distinguished by MASS SPECTROSCOPY :- → Mass spectroscopy is a powerful analytical technique that deals with The determinilion of elementary composition of a sample upon Converting it to rapidly moving charged particles Mass spectrometry was previously known as mass spectroscop PRINCIPLE:- → When a compound is exposed to a high voltage electric current it losses electrons and gets converted to msitiysly charged The basic magnēlic or electric field acting on this moving charged ions [Positive tre ions] deflects them along circular path a radius that is ratio that is mle. a function of their mass (m) to chargele) FRAGMENTATION:- →the charged fragmented products may themselves undergo further pragmentation to give Products. smaller charge as well as neutral →The relalive abundance of positively charged fragments of various mass to charge ratios is the characteristic feature of the molecule and can serve to identify the substance. METASTABLE IONS :- The molecular ions produced by the bombardment of electron may be stable of unstable. the stribe ions remain as such, but the unstable ions undergo decomposition into smaller pragments. MULTIPLE CHARGED JONS:- The ions produced in the mass spectrum when two or more carry a single charge but carry electrons are removed from a molecule, the ions produced may have double triple charges respectively. NEGATIVE JONS:- Negative ions are usually ignored as they the analysis of compounds. ave of a no helpin