Comments on phosphorescence decay times of benzene and methyl-benzene derivatives
β Scribed by J.W. Rabalais; H.J. Maria; S.P. McGlynn
- Publisher
- Elsevier Science
- Year
- 1969
- Tongue
- English
- Weight
- 190 KB
- Volume
- 3
- Category
- Article
- ISSN
- 0009-2614
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β¦ Synopsis
It is shown that methyl substitution in benzene increases (T. v-mixing to an extent which is readiLy observable in the intrinsic phcsphorescence lifetime. It is also shown that C-H vibrational modes which are esternal to the benzene ring (i. e. in the CH3 group) contribute to phosphorescence quenching-Fina&. some recently reported 'relaxation effects ' are shown to be caused by poor temperature controls.
π SIMILAR VOLUMES
Flyorescence decay times of the di-, tri-, tetra-and pentwnethyl benzenes and the three isomeric difiuorobenzencs have been rncnsured at low pressures. The substitucnt effects of CH3+roups and F-atom (in benzene) on the nonrndiativc rate ofrhc "isolated" ascited singlet molecule are briefly discusse
The CNDO,5 method of de1 Bent and Jaff6 has been applied to the study of the triplet-triplet absor;?tion of ;eq;jne and omc methylated derivatives. The fist allowed triplet-triplet transition in benzene is assigned to the J%g + 3Bd transition.
The incrwsc m the pl~osphorusccncc litctunc 'IS tcrnperaturc IS lowcrcd has been quantitatwely detcnnined m the 2-30 K range. Applying Ulc Bolt7mann population c\prcssion yreld\ the infcrmlatron that virtually none of the radratwe decay orign.ltes from the lowest Fpm sublcvcl (A-$ \*