Time Evolution of the Excimer State of a Conjugated Polymer Laser.

An excited dimer is an important complex formed in nano- or pico-second time scales in many photophysics and photochemistry applications. The spectral and temporal profile of the excimer state of a laser from a new conjugated polymer, namely, poly (9,9-dioctylfluorenyl-2,7-diyl) (PFO), under several concentrations in benzene were investigated. These solutions were optically pumped by intense pulsed third-harmonic Nd:YAG laser (355-nm) to obtain the amplified spontaneous emission (ASE) spectra of a monomer and an excimer with bandwidths of 6 and 7 nm, respectively. The monomer and excimer ASEs were dependent on the PFO concentration, pump power, and temperature. Employing a sophisticated picosecond spectrometer, the time evolution of the excimer state of this polymer, which is over 400 ps, can be monitored.