Question

discuss three different types of interaction of radiation with matter used in optical instruments giving examples of the instruments based on those interactions

Answer 1

The interaction of radiation with matter depends on the nature of interaction and this may be

1. Absorption -

This occurs when the energy from radiation source is absorbed by the matter. The absorbance is determined by amount of light transmitted from the matter. This is the principle used in UV-Visible Spectroscopy.

Eg. UV-Visible Spectrophotometers are based on the principle of Absorption of radiation by matter.

2. Emission -

When the molecule excites from ground to excited state and returns back to ground state, there is emission of the radiation. This gives emission spectrum. It is known as Emission Spectroscopy. This is the principle used in X-ray Emission spectroscopy, Fluorescence Spectroscopy.

Eg. Fluorimeter, X-Ray Spectrometer.

3. Elastic Scatterig -

When the radiation interacts ith the matter, there is scattering of the incident radiation. The scattering might be elastic or inelastic scattering. This is the principle used in Crystallography where the high energy incident radiation is scattered by X-rays and electrons, thus giving the arrangememnt of atoms in the crytsal lattice.

Eg. X-ray diffraction Crystallographer