Inorganic Chemistry

Rotational Spectroscopy 1.  What is the degeneracy of the rotational energy level with  J  = 4 for a heteronuclear diatomic molecule? 2. The  A  rotational constant of a phosphorus pentafluoride, PF 5 , molecule is 3.566 Hz. Calculate the lengths of the equatorial P-F bonds. 3. The rotational constant of ICl is 0.1142 cm-1. Calculate the bond length of the molecule. 

Introduction to spectroscopy: part 2 Rotational spectroscopy electromagnetic radiation lies in the microwave region ( λ = 30cm – 3mm) of the electromagnetic radiation spectrum. Rotational spectroscopy is applicable only for the molecules with a dipole moment. Samples are usually in gaseous state. Rigid diatomic molecules; A general equation can be derived using Schrödinger equation for a rigid rotor. Planck's constant = 6.626 × 10 -34 m 2 kg / s Normally Energy is given in the term of ṽ Selection Rules for a rigid rotor Needs a permanent dipole moment. only polar molecules can give a pure rotational spectrum. Only #1 type transitions can be used for rotational spectra. #2 can not be used. Spacing between Energy Levels The Energy gap between two energy levels is given by the equation which is derived below. The table 01: Rotational Energy levels Spectral lines: Moment of Iner...