Title :
Relaxation dynamics of photoexcitations in polydiacetylene films
Author :
Yoshizawa, Masayuki ; Taiji, M. ; Kobayashi, Takayoshi
Author_Institution :
Dept. of Phys., Tokyo Univ., Japan
fDate :
12/1/1989 12:00:00 AM
Abstract :
The relaxation dynamics of photoexcitations in a polydiacetylene (poly-3BCMU) film was investigated by femtosecond time-resolved absorption spectroscopy. Spectral change due to several nonlinear optical processes, i.e. hole burning, Raman gain, and dynamic Stark effect, was observed. The difference absorption spectra of singlet and triplet excitons minus ground state were measured. The photoexcited singlet excitons relaxed to the self-trapped state with the time constant of 150±50 fs. The lifetime of the self-trapped excitons was 2.0±0.1 ps at 10 K and 1.5±0.2 ps at 290 K. The lifetime of the triplet excitons was much longer than several tens of picoseconds and was consistent with the lifetime of 18 μs obtained by nanosecond spectroscopy
Keywords :
Stark effect; excitons; high-speed optical techniques; optical hole burning; polymer films; time resolved spectra; visible spectra of organic molecules and substances; 1.5 ps; 10 K; 150 fs; 18 mus; 2 ps; 290 K; Raman gain; difference absorption spectra; dynamic Stark effect; exciton lifetime; exciton relaxation; femtosecond time-resolved absorption spectroscopy; ground state; hole burning; nanosecond spectroscopy; nonlinear optical processes; photoexcitations; photoexcited singlet excitons; poly-3BCMU film; polydiacetylene films; relaxation dynamics; self-trapped excitons; self-trapped state; singlet excitons; spectral changes; time constant; triplet excitons; Absorption; Excitons; Kinetic theory; Optical films; Optical polymers; Optical solitons; Polymer films; Spectroscopy; Stationary state; Ultrafast optics;
Journal_Title :
Quantum Electronics, IEEE Journal of
