Question

rotational fine structure of vibration-elctronic spectra
​

Answer 1

Each electronic transition may show vibrational coarse structure, and for molecules in the gas phase, rotational fine structure. ... The emission spectrum is more complicated than the absorption spectrum of the same molecule because there are more changes in vibrational energy level.

Rotational–vibrational spectroscopy:-

Rotational–vibrational spectroscopy is a branch of molecular spectroscopy concerned with infrared and Raman spectra of molecules in the gas phase. Transitions involving changes in both vibrational and rotational states can be abbreviated as rovibrational transitions.