  We used a variety of nonlinear optical (NLO) spectroscopies to study the
singlet excited states order, and primary photoexcitations in polyfluorene; an
important blue emitting p-conjugated polymer. The polarized NLO spectroscopies
include ultrafast pump-probe photomodulation, two-photon absorption, and
electroabsorption. For completeness we also measured the linear absorption and
photoluminescence spectra. We found that the primary photoexcitations in
polyfluorene are singlet excitons.
