Emission gain narrowing from single crystals of a thiophene/phenylene co-oligomer

Emission gain narrowing has been observed for single crystals of a thiophene/phenylene co-oligomer. The hexagon flake crystals were placed on a quartz substrate with the crystals’ face in close contact with the substrate plane. These crystals were irradiated with a N2 laser with a 337.1 nm wavelength at a repetition rate 10 Hz that tuned its intensity to 100–1150 μJ/cm2. The emission gain narrowing takes place at 21490 (465.4 nm) and 20220 cm−1 (494.5 nm) with increased intensities, with their half width at half maxima reaching ∼50 cm−1. On the basis of the nonlinear relationship between the emission peak intensities and the laser light intensity, the gain narrowing has been attributed to the amplified spontaneous emission.