[OPTICAL REVIEW Vol. 17, No. 3 (2010) 337-340]
© 2010 The Japan Society of Applied Physics

Nonlinear Absorption Microspectroscopy of Single Perylene Nanocrystals with a Multichannel Double Lock-In Amplifier

Heisuke ISHINO1, Shigeto IWAI1, Shunji IWAMOTO1, Tsuneo OKUMURA1, Takayoshi KOBAYASHI2, and Eiji TOKUNAGA1,3

1Department of Physics, Faculty of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
2Department of Applied Physics and Chemistry, and Institute for Laser Science, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan
3Research Center for Green Photo-Science and Technology, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo 162-8601, Japan

(Received September 19, 2009; Accepted January 4, 2010)

Nonlinear confocal absorption microspectroscopy of single nanocrystals at low temperatures was introduced in the study of perylene nanocrystals. By the stationary pump–probe method, single nanocrystals were photoexcited into metastable excited states, and difference absorption spectra due to excited-state absorption and ground-state depletion were simultaneously recorded using a multichannel lock-in amplifier. It was revealed that the free Frenkel exciton band for single perylene nanocrystals is broader in width than that for the bulk crystal at low temperatures, suggesting that the exciton band is inhomogeneously broadened even for single perylene nanocrystals.

Key words: perylene, single nanocrystal, single nanoparticle spectroscopy, molecular crystal, low temperature, confocal microspectroscopy, organic molecule, nonlinear absorption, Frenkel exciton, self-trapped exciton