In the cavity ring-down measurement at the opening of this chapter, absorbance is given by

where L is the length of the cavity between mirrors, c is the speed of light,t is the ring down lifetime with sample in the cavity, and T0 is the ring-down lifetime with no sample in the cavity. Ring-down lifetime is obtained by fitting the observed ring-down signal intensity I to an exponential decay of the form I = I0e-t/t, where I0 is the initial intensity and t is time. A measurement of CO2 is made at a wavelength absorbed by the molecule. The ring down lifetime for a 21.0-cm-long empty cavity is 18.52 μs and 16.06 μs for a cavity containing CO2. Find the absorbance of CO2 at this wavelength.

Transcribed Image Text:

L. c In 10 TO.