Excited-state polarizability of J-aggregates

The difference between the static polarizabilities of the first excited and the ground state of J-aggregates has been derived using the sum-over-states approach. For a simple model analytical expressions as well as numerical calculations show that the polarizability enhancement upon excitation should depend only marginally on the aggregate size. Charge-transfer states have been suggested as the possible origin of the observed large excited-state polarizabilities of J-aggregates.