The photochemical formation of secondary triplet spin systems from primary triplets in single crystals of photochromic 2,3,4,4-tetrachloro-1-keto-1,4-dihydronaphthalene (β-TKN)

✍ Scribed by F.P.A. Zweegers; C.A.G.O. Varma

• Publisher: Elsevier Science
• Year: 1979
• Tongue: English
• Weight: 496 KB
• Volume: 61
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(79)87172-9

✦ Synopsis

Irmdktrion ofsir@e crystnfs of photochromic p-TRN u ith UV tight yields initiehy a tripIet spin system. arising from spin c~uphng between trio redice& Iouted on nei&bourinS httice sites. After prolonged irradiation. free radicals and another triplet spin system are observed in the ESR spectrum. The new tripIet spin system, characterized by D = z48.6 G and E = 20.9 G. is attributed to zc radkd pair formed from two &TKN molecuIes, which me crysttiogmphicnhy equivalent .md SC pnmted by one Iattice distxtce niong the b-n_xis. The formotion of primary and secondary ndical pairs is caused by sequen-tin& shifting. n CI atom, by .tbsorption of light, from one @-TKN molecule to the ne.xt one within s chein of moleeuIes sticked zIo% the b-r&r_