The increase in transmission coefficient at high fluences, following l
ow-fluence reverse saturable absorption (induced absorption), is demon
strated for the tricarbocyanine dye, HITCI. This novel effect is expla
ined in terms of a modified three-level model of the singlet states. T
he absorption cross-section at 532 nm of the first excited state is de
termined to be 4.8 x 10(-16) cm2, 29 times that of the ground state. W
e find the lifetime of the first excited state to be 1.5 ns and that o
f the second excited state to be of the order of 8 ps.