[UPSC CSE 2003] Molecular Physics (Q269, 6+14M)

(i) What are the typical energies (eV) of the radiations, required to excite (i) electronic transitions. (ii) vibrational transitions and (iii) rotational transitions in a molecule ? (ii) The rotational spectrum of HI consists of equidistant lines with a separation of 12.8\text{ cm}^{-1}. Calculate the (a) M.I. and (b) bond length of HI molecule.