By Sunil Bhardwaj


Spectroscopy is the branch of science which deals with the study of interaction of electromagnetic radiation with matter.

Because of such interaction the matter absorbs or emits the energy in discrete amounts called "quanta".

The molecule has always characteristic electronic, vibrational and rotational energy levels.

The difference between the electronic energy level is very large and hence the spacing between \(E1\) and \(E2\) is large. The difference between two electronic energy levels goes on decreasing. \(i.e. \ (E2 - E1) > (E3 - E2),\) \((E3 - E2) > (E4 - E3)\) and so on.

Each electronic energy level is further sub-divided into group of vibrational energy levels i.e., between \(E1\) and \(E2\) there are \(V0, V2, V3.... Vn\) vibrational energy levels. The difference between two vibrational energy levels goes on decreasing \(i.e. \ (V1 - V0) > (V2 - V1),\) \((V2 - V1) > (V3 - V2)\) and so on.

Each vibrational energy levels are further sub - divided into number of rotational energy levels. i.e. \(J0, J1, J2, ...... Jn\). The difference between two rotational energy levels goes on increasing. \(i.e. \ (J1 - J0) < (J2 - J1),\) \((J2 - J1) < (J3 - J2)\) and so on.

When there is a change in the electronic energy levels, there will be simultaneous change in vibrational and rotational energy levels. The total energy absorbed causes simultaneous changes in electronic transition, vibrational changes and rotational changes.

MCQ on Spectroscopy from Physical Chemistry
Prof. Gianfranco Coletti

Shared publicly - 2019-08-23 00:00:00

Don’t want your columns to simply stack in some grid tiers? Use a combination of different classes for each tier as needed. See the example below for a better idea of how it all works.

Prof. Maheshwar Sharon

Shared publicly - 2019-08-24 00:00:00

For grids that are the same from the smallest of devices to the largest, use the .col and .col-* classes. Specify a numbered class when you need a particularly sized column; otherwise, feel free to stick to


Shared publicly - 2023-02-28 11:09:52

this is


Shared publicly - 2023-02-28 10:48:10