Excited electronic states of the fluorobenzenes by variable angle electron impact spectroscopy

✍ Scribed by Robert P. Frueholz; Wayne M. Flicker; Oren A. Mosher; Aron Kuppermann

• Publisher: Elsevier Science
• Year: 1977
• Tongue: English
• Weight: 639 KB
• Volume: 52
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(77)85126-9

✦ Synopsis

l:icctron-mqaact excitation pectra of benzcnc. fluorobenrcne, o-difluorobcnzene, 1,3,5-trinuorobcn~ene. 1,2,3,4-tetrafluorobcnzcnc, pcntafluorobenzcne, and hexatluorobenzenc have been measured at impact cncrgics of 50 eV and either 25 cV or 30 cV, and scatcrmp nngles from 5' to 80". Lath molecule shows an absorption tna-amum at about 3.9 eV correspondlng to ;I stnglct + triplet, 7il n*, transition. In bencenc, fluorobenzene, o-difluorobenrcnc, and 1,3,5-trtfluorobenzne, rln aidlrional =nglCt -+ triplet transition was detected at about 5.6 cV. Three singlet -r singlet transitions analogous to the 4.90, 6.20, and 6.95 eV transitions in bcnrcnc arc seen in each of the tlttortne-sub~titoted molecules. Tbc mote highly \rrbstttutcd cornpounds exhibit an additronal sin&t ' 1 -sillgkt trrutsitton that is most clcaly observed in the heu:rfluorobenzenc spectrum with a peak at 5.32 cV The experimental technique of low-energy, variablcangle, electron-impact spectroscopy [ 11 has been apphetl to fluorine-substltutcd benrcncs which have from one to six fluorine atoms. The goals of this investigation were lo locate singlet -+ triplet electronic transitions, to determine their electroruc band shapes, and to invcstrgate the ctfects of fluorme substilutml on the electronic transitIons ot' the sr-clcctroii ring.