Open Access

Manfred Wilk, Karl-Heinz Peters

• Investigations were made of energy-transfer in liquid scintillators under UV- and β-excitation. The influences of n-hexane and methanol as diluting solvents on the scintillation process in p- terphenyl-toluene were measured. Differences of energy transfer under β - and UV-irradiation are discussed. Radiationless energy-transfer occurs over distances from 15 to 32 Angström units. Quenching effects of phenol on p-terphenyl, 2,5-diphenyl-oxazole, and 2,4 (or 5) -diphenyl-imidazole were studied. Oxygen-quenching in liquid scintillators containing hydroxy-benzenes was investigated. The results are in correspondence with the KALLMANN-mechanism of radiationless energy-transfer. — Further investigations were made of the connection between the chemical structure of aryl-imidazoles and their scintillation properties. Scintillation properties depend on spectral data. The results aprove HELLERS postulates, concerning structural requirements for good scintillation properties of organic liquid scintillators.