Influence of energetic excitation on the structure and location of the radical II in X-irradiated Rochelle salt studied by ENDOR

Abstract

ENDOR investigations of the radical II in X-irradiated Rochelle salt have been performed at 77 K. The number of lines observed is twice that anticipated from symmetry considerations. This fact might indicate the existence of two kinds of radical which differ from each other only slightly and are distinguished by their excitation energy. The excitation is accompanied by an increase in the OH bond length. The original hydrogen bond O 6H…O 2 ′ is modified to O 6H…O l ′, where O 1 ′ and O 2 ′ represent the atoms of the carboxyl group of the adjacent unit cell. This bond lacks stability. The measurement of the intensity dependence of the lines on the time after irradiation gives evidence of the recombination of the radical after excitation.