M. Furuki et al., MONOMOLECULAR LAYER OF SQUARYLIUM DYE J-AGGREGATES EXHIBITING A FEMTOSECOND OPTICAL-RESPONSE OF DELOCALIZED EXCITONS, Applied physics letters, 72(21), 1998, pp. 2648-2650
We report on the demonstration of the femtosecond nonlinear optical re
sponse from a two-dimensional monomolecular layer of squarylium dye J
aggregate at 5 degrees C. The formation of a monomolecular layer Langm
uir film was achieved by spreading squarylium dye modified by two prop
yl and two hexyl groups at the air-water interface, which resulted in
a very strong J band (o.d.=0.3) at 777 nm, The transient absorption sp
ectra in a resonant pump-probe measurement showed a low absorption sat
uration power (9.7X10(6) W/cm(2)) and an ultrafast response (300 fs),
which are indicative of exciton delocalization over is molecules in th
is J aggregate, even at 5 degrees C. (C) 1998 American Institute of Ph
ysics.