We measured the gain spectrum of red perylimide dye (RPD) dissolved in cyclohexane. A frequency-doubled Nd: YAG laser at 1 Hz repetition rate was used for pumping. A probe pulsed laser beam was obtained using a series of laser-grade dyes. Gain is observed in the region 550-660 nm and loss in the region 660-730 nm. The loss is interpreted as absorption from the first singlet excited state S1to a higher singlet excited state Sn. The cross section σ1nis calculated as 1.3 × 10-16cm2/ molecule in the region 550-660 nm and 5 × 10-17cm2/ molecule in the region 650-710 nm. This process competes with the stimulated emission to a lower state, which establishes the mechanism for the dye-laser action. © 1993.
Gvishi, R., Reisfeld, R., & Burshtein, Z. (1993). Excited-state absorption in red perylimide dye in solution. Chemical Physics Letters, 212(5), 463–466. https://doi.org/10.1016/0009-2614(93)87229-V