Question

1. What is the main difference between fluoroscopy and spectroscopy?
2. What do you understand from Laue condition? Discuss
3. Describe what you understand from continuous radiation?
4. Describe what you understand from characteristic radiation?

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Answer 1

A) Fluoroscopy is a type of medical imaging that shows a continuous X-ray image on a monitor, much like an X-ray movie. During a fluoroscopy procedure, an X-ray beam is passed through the body. The image is transmitted to a monitor so the movement of a body part or of an instrument or contrast agent (“X-ray dye”) through the body can be seen in detail.

The term "spectroscopy" defines a large number of techniques that use radiation to obtain information on the structure and properties of matter. The basic principleshared by all spectroscopic techniques is to shine a beam of electromagnetic radiation onto a sample, and observe how it responds to such a stimulus.

B) Laue equation and conditions-

Let a,b,c be the primitive vectors of the crystal lattice L,whose atoms are located at the points x,=pa+qb+rc that are integer linear combinations of the primitive vectors.

Let Kin be the wavevector of the incoming (incident) beam, and let Kout be the wavevector of the outgoing (diffracted) beam. Then the vector Kout-Kin=∆K is called the scattering vector (also called transferred wavevector) and measures the change between the two wavevectors.

The three conditions that the scattering vector ∆K must satisfy, called the Laue equations, are the following: the numbers (h,k,l) determined by the equations

a. ∆K=2πh

b. ∆K=2πk

c. ∆K=2πl

must be integer numbers. Each choice of the integers( h,k,l)called Miller indices, determines a scattering vector ∆K.Hence there are infinitely many scattering vectors that satisfy the Laue equations. They form a lattice L*, called the reciprocal lattice of the crystal lattice. This condition allows a single incident beam to be diffracted in infinitely many directions. However, the beams that correspond to high Miller indices are very weak and can't be observed. These equations are enough to find the basis of reciprocal lattice,from which the crystal lattice can be determined.This is the principle of x-ray crystallography.

C) continous radiation--Electromagnetic radiation that include all the wavelengths in some interval.It is also known as white radiation.rainbow is an example of a continuous spectrum. Most continuous spectra are from hot, dense objects like stars, planets, or moons. The continuous spectrum from these kinds of objects is also called a thermalspectrum, because hot, dense objects will emit electromagnetic radiation at all wavelengths or colors.

D)When a fast-moving electron collides with a K-shell electron, the electron in the K-shell is ejected (provided the energy of the incident electron is greater than the binding energy of K-shell electron) leaving behind a 'hole'. An outer shell electron fills this hole (from the L-shell, M-shell, etc. ) with an emission of a single x-ray photon, called characteristic radiation, with an energy level equivalent to the energy level difference between the outer and inner shell electron involved in the transition.