**Questions and Answers for chapter 7:**

1. Question: In page-15, can the amplitude of the oscillating dipole be estimated from the breadth/length of the LUMO of the given molecule?

Answer: Yes if the transition is allowed. The size of the oscillating dipole is equal to the charge displacement in going from the ground state to the excited state when the transition is fully allowed. When it is forbidden the classical picture breaks down sometimes completely, i.e., for singlet triplet transitions and symmetry forbidden transitions.

2. Question: Is there a detailed reference that shows how the spectral overlap is introduced in the term for Columbic energy transfer?

Answer: Good questions. IÕll look for a reference and weÕll put in on the course home page.

3. Question:
In page-19 is R_{o}^{DA} the distance at which all the donors
transfer energy to the acceptors? In that case how do we arrive at the term
6.5[A]^{1/3}.

Answer: This
comes out the approximation relating the radius of a quenching sphere and the
concentration of an acceptor: R = (3V/4p)^{1/3}
= 6.5 [A]^{1/3} where A is the concentration of acceptor in M and R is
the radius in .

4. Question: In Page-25, could the process of arriving at the spin statistics for different types of encounters be explained a little more?

Answer: Use the model of the spin vector to see how many different orientations are possible from various combinations of spins. For a single spin there are only two (up and down). For two spins, you know there are four states, a singlet and three levels of a triplet. Try to figure out how many distinct spin states there are for three spins and for four spins. (Hint: there will be a quartet and a doublet for a total of five distinct spin states for the three spin system and a singlet, a triplet and a quintet for a total of nine states for four spins.