Contribution of electronically excited states to the radiation chemistry of organic systems. Progress report, December 1, 1981-November 30, 1984. [Tetramethyl-p-phenylenediamine]
The fluorescence of saturated hydrocarbon liquids excited by /sup 85/Kr beta particles has been studied as a function of the concentration of electron scavenger. It has been possible to extract the probability, p/sup +/, that the scavengers attach a geminate electron. The effect of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) to scavenge geminate positive ions in irradiated hydrocarbon liquids has been studied via examination of the recombination fluorescence of TMPD/sup +/ + e/sup -/ as a function of TMPD concentration. The scavenging probability p/sup +/ is found to be simply proportional to c. An effect of electron scavengers to reduce the photocurrent from TMPD excited optically above its ionization threshold in nonpolar liquids has been observed and explained in terms of interaction of the scavenger with epithermal electrons. The field and temperature dependences of the photocurrent has been studied in the presence and absence of electron scavengers and the results support the epithermal model. The fractional reduction in TMPD fluorescence in liquid tetramethylsilane caused by imposition of an electric field has been studied as a function of excitation energy (above the photoionization threshold) and as a function of field strength. It has been possible to extract the photoionization quantum yield and the electron thermalization range from approx. = 5.5 eV to 7.5 eV. From an absolute measurement of the yield of excited solute states in irradiated benzene and comparison with optical measurements, it is concluded that the energy transfer efficiency is representable by a Stern-Volmer function that extrapolates to unity at infinite solute concentration. The excimer to monomer ratio in photoexcited polystyrene in solution is found not to depend on polystyrene concentration.
- Research Organization:
- Minnesota Univ., Minneapolis (USA)
- DOE Contract Number:
- AC02-76ER00913
- OSTI ID:
- 6154777
- Report Number(s):
- DOE/ET/00913-3; ON: DE85004311
- Country of Publication:
- United States
- Language:
- English
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Effect of electron scavengers to reduce the ionization current of photoexcited N,N,N',N'-tetramethyl-p-phenylenediamine in nonpolar organic liquids
Photoionization yield and electron thermalization range spectra of N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) in tetramethylsilane
Related Subjects
AMINES
FLUORESCENCE
POLYSTYRENE
RADIATION CHEMISTRY
EXCITED STATES
RESEARCH PROGRAMS
BENZENE
BETA PARTICLES
ELECTRIC FIELDS
EXCITATION
HYDROCARBONS
ION PAIRS
LIQUIDS
PHOTOIONIZATION
RECOMBINATION
SCAVENGING
SILANES
AROMATICS
CHARGED PARTICLES
CHEMISTRY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
FLUIDS
HYDRIDES
HYDROGEN COMPOUNDS
IONIZATION
LUMINESCENCE
MATERIALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
ORGANIC SILICON COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYMERS
POLYOLEFINS
POLYVINYLS
SILICON COMPOUNDS
SYNTHETIC MATERIALS
400600* - Radiation Chemistry