| The cumulative intensity graphs (shown above) help us to fit a dynamic rotational spectrum to an isomerization rate. The cumulative intensity of the 4-fluorobutyne triple resonance spectrum is plotted separately for the J = 2>1 and the J = 2>3 transitions. In both cases an isomerization lifetime of 37 ps produces an analytic lineshape which fits the data well. The ground state frequencies for the two isomers (gauche and trans) are shown as vertical reference lines. It is clear that the center of intensity in the triple resonance spectrum is not centered around the gauche or the trans ground state frequency, but rather between the two, indicating that the molecule is undergoing an isomerization reaction. |