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

All vibrations producing a change in the electric dipole moment of a molecule yield

A piece of paraffin is placed in a uniform magnetic field H₀. The sample contains hydrogen nuclei of mass m_p, which interact only with external magnetic field. An additional oscillating magnetic field is applied to observe resonance absorption. If g₁ is the g-factor of the hydrogen nucleus, the frequency at which resonance absorption takes place, is given by

Consider the following statements about molecular spectra:
P. CH₄ does not give pure rotational Raman lines
Q. SF₆ could be studied by rotational Raman spectroscopy
R. N₂ shows infrared absorption spectrum
S. CH₃CH₃ shows vibrational Raman and infrared absorption lines
T. H₂O₂ shows pure rotational spectrum
Choose the right combination of correct statements.

The hyperfine structure of Na(3²P_3/2) with nuclear $$l$$ = 3/2 has