A vibrational-electronic spectrum of homonuclear binary molecules, involving electronic ground state ε'' and excited ε', exhibits a continuum at $$\overline v $$ cm-1. If the total energy of the dissociated atoms in the excited state exceeds the total energy of the dissociated atoms in the ground state by Eex cm-1, then dissociation energy of the molecule in the ground state is

For a multi-electron atom $$l$$, L and S specify the one electron orbital angular momentum, total orbital angular momentum and total spin angular momentum respectively. The selection rules for electric dipole transition between the two electronic energy levels, specified by $$l$$, L and S are

Two states of an atom have definite parities. An electric dipole transition between these states is

A collection of N atoms is exposed to a strong resonant electromagnetic radiation with Ng atoms in the ground state and N atoms in the excited state, such that Ng + Ne = N. This collection of two-level atoms will have the following population distribution

Deuteron in its ground state has a total angular momentum J = 1 and a positive parity. The corresponding orbital angular momentum L and spin angular momentum S combinations are

Two monochromatic waves having frequencies $$\omega $$ and $$\omega + \Delta \omega \left( {\Delta \omega \ll \omega } \right)$$    and corresponding wavelengths $$\lambda $$ and $$\lambda - \Delta \lambda \left( {\Delta \lambda \ll \lambda } \right)$$    of same polarization, travelling along X-axis are superimposed on each other. The phase velocity and group velocity of the resultant wave are respectively given by

A pure rotational Raman spectrum of a linear diatomic molecule is recorded using electromagnetic radiation of frequency $${\nu _e}$$ . The frequency of two consecutive Stokes lines are

The rotational partition function for a diatomic molecule of moment of inertia $$I$$ at a temperature T is given by