Comprehensive photoluminescence-detected magnetic-resonance study of C{sub 60} and C{sub 70} glasses and films
- Ames Laboratory U.S. Department of Energy and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
The {ital X}-band photoluminescence-detected magnetic resonance (PLDMR) of C{sub 60} and C{sub 70} films and molecules isolated in toluene/polystyrene glasses is described. The PLDMR of the glasses is due to a triplet exciton delocalized over the entire molecule. However, the PLDMR of triplet-state C{sub 70} ({sup 3}C{sub 70}) strikingly differs from that of {sup 3}C{sub 60} in both line shape and dynamics, due to the much longer lifetime of {sup 3}C{sub 70} which is consequently phosphorescent. Two distinct types of triplet excitons are detected in the PLDMR of fullerene films, one similarly delocalized over the entire molecule and a second believed to be localized on a pentagon or hexagon face adjacent to a neighboring molecule. The PLDMR line shape of the delocalized triplet is distorted due to intermolecular interactions and half-field resonances consistent with triplet-triplet fusion are detected for both triplets. A narrow ({lt}5-G-wide) PL-enhancing resonance at {ital g}=2.0017 for C{sub 60} and 2.0029 for C{sub 70} is observed and attributed to recombination of long-lived charged polarons. The PLDMR of photo-oxidized and photopolymerized films of C{sub 60} and C{sub 70} is also described. Both processes quench the PLDMR of the localized triplet, but the spectra of photopolymerized C{sub 60} films reveal the possibility of a third triplet exciton delocalized across several molecules.
- Research Organization:
- Ames National Laboratory
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 46352
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 15 Vol. 51; ISSN 0163-1829; ISSN PRBMDO
- Country of Publication:
- United States
- Language:
- English
Similar Records
Dynamics of photoexcited states in C sub 60 : An optically detected magnetic resonance, ESR, and light-induced ESR study
Optically detected magnetic-resonance study of triplet-state dynamics in C{sub 70}