Chapter 11, Problem 11A.11P

Interpretation Introduction

Interpretation:

The expression for the collision limited lifetime of an excited state if every collision is effective has to be stated.  The width of the rotational transition of $\text{HCl}$ molecule has to be stated.  The value to which the pressure of the gas should be reduced such that collision broadening is less important than Doppler broadening has to be calculated.

Concept introduction:

The change in the frequency or wavelength of waves when the source and observer move with respect to each other is known as the Doppler effect.  The Doppler effect causes the change in received wavelength of waves as compared to source and the new wavelength is known as the Doppler shifted wavelength.  The broadening of the spectral lines due to the Doppler effect is known as Doppler broadening.