PHOTOSTIMULATED STRUCTURAL-CHANGES IN YELLOW ARSENIC

DTA and ESR methods were applied for studying photostimulated changes in molecular arsenic (y-As). It is shown that under the effect of illu mination/irradiation the stability of y-As decreases, which is due to the formation of stable fragments of the polymeric phase (a-As). Using the principles of orbital symmetry conservation, it is shown that pol ymerization takes place most favourably from a staggered 'face to face ' configuration of As-4 molecules. Photopolymerization may proceed wit hout activation. As a result we get a formation of an intermediate mol ecular cluster As-8 of 'chairlike' symmetry D-2h.