Chapter 14, Problem 14.89E

Interpretation Introduction

Interpretation:

Whether the equivalent of $P$, $Q$, or $R$ branches appear in electronic spectra if $\Delta v$ are $-1$, $0$, or $1$ is to be stated.

Concept introduction:

An electronic state of energy has its own vibrational states. The energy between the electronic states is large followed by vibrational states and then rotational states. During an electronic transition, electron from ground state moves straight to the excited state keeping the internuclear distance constant.