Estimate the oscillator strength (see Problem 14.16) of a charge transfer transition modeled as the migration of an electron from an His orbital on one atom to another His orbital on an atom a distance R away. Approximate the transition moment by -eRS where 5 is the overlap integral of the two orbitals. Sketch the oscillator strength as a function of R using the curve for 5 given in Fig. 11.29. Why does the intensity fall to zero as R approaches 0 and infinity?