Chapter 8, Problem 8.8QAP

The Doppler effect is one of the sources of the line broadening in atomic absorption spectroscopy. Atoms moving toward the light source encounter higher-frequency radiation than atoms moving away from the source. The difference in wavelength $\Delta \lambda$ experienced by an atom moving at speed v (compared to one atrest) is $\Delta \lambda$ / $\lambda$ = v/c , where c is the velocity of light. Estimate the line width (in nanometers) of the lithiumline at 670.776(6707.76 Å) when the absorbing atoms are at a temperature of (a) 2000 K and (b) 3120 K.The average speed of an atom is given by $v=\sqrt{8kT/\pi m}$ , where k is Boltzmann’s constant, Tis the absolute temperature, and m is its mass.