Chapter 11, Problem 11.8P

(a)

Interpretation Introduction

Interpretation:

Number of vibrational modes in $H_2{O}_2$ if the molecule was linear has to be determined.

Concept Introduction:

Number of vibrational modes in a polyatomic molecule is given by,

  $\begin{array}{c}{\text{N}}_{\text{vib}}\text{= 3N}-\text{6}\left(\text{For nonlinear molecules}\right)\\ \\ {\text{N}}_{\text{vib}}\text{= 3N}-5\left(\text{For linear molecules}\right)\\ \\ where,\text{ N is the no}\text{. of atoms}\end{array}$

(b)

Interpretation Introduction

Interpretation:

Conformations that are inconsistent with the given spectroscopic datas have to be determined.

Concept Introduction:

Selection rule for vibrational spectrum:

During the vibration, the electric dipole moment of the molecule should change.

Gross selection rule for vibrational Raman spectra:

A normal mode is vibrational Raman active, if the motion causes the change in polarizability of the molecule.

According to exclusion rule, no modes can be both infrared and Raman active in a molecule when if it contains a center of inversion.