Light-induced electron transfer vs. energy transfer in molecular thin-film systems
Conference
·
OSTI ID:5182978
Quenching of fluoranthene (FA) singlets by tetrabromo-o-benzoquinone (TBBQ) and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was studied both in xylene solutions and in spin-cast polystyrene (PS) films. Emphasis was placed on time-resolved fluorescence transients resulting from pulsed excitation. Linear Stern-Volmer plots were obtained for quenching in solution and gave diffusion-controlled rate constants, of 1.45 x 10/sup 10/ M/sup -1/ sec/sup -1/ and 1.53 x 10/sup 10/ M/sup -1/ sec/sup -1/ for TBBQ and TMPD, respectively. TBBQ was found to quench FA singlets in PS over the studied concentration range 12 mM < (TBBQ) < 48 mM, but in its presence FA singlets decayed nonexponentially. The results were interpreted quantitatively in terms of pure Foerster's transfer from FA to TBBQ without diffusion of excitons. The critical transfer radius R/sub 0/ was experimentally determined to be 24.3 A, which is in good agreement with the theoretical value of 23 A calculated from spectral data. Quenching of FA singlets in PS films was found to be independent of FA concentration over a 300 mM to 1200 mM FA concentration range for a constant TBBQ concentration of 24.0 mM. TMPD was only slightly effective as a quencher of FA singlets in PS because it apparently behaves strictly as a contact quencher based on reversible charge transfer. The implications of these results for the design of systems intended to exploit light-induced electron transfer are discussed.
- Research Organization:
- Illinois Univ., Urbana (USA)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 5182978
- Report Number(s):
- DOE/ER/01198-1306; CONF-800905-1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
AROMATICS
CHEMISTRY
CONDENSED AROMATICS
ELECTRON TRANSFER
ENERGY LEVELS
EXCITED STATES
EXCITONS
FILMS
FLUORESCENCE
HYDROCARBONS
LUMINESCENCE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHOTOCHEMISTRY
PLASTICS
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
QUASI PARTICLES
QUENCHING
XYLENES
400500* -- Photochemistry
AROMATICS
CHEMISTRY
CONDENSED AROMATICS
ELECTRON TRANSFER
ENERGY LEVELS
EXCITED STATES
EXCITONS
FILMS
FLUORESCENCE
HYDROCARBONS
LUMINESCENCE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PHOTOCHEMISTRY
PLASTICS
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
QUASI PARTICLES
QUENCHING
XYLENES