ENDOR Investigation of Cu⁺⁺ Centres in NH₄Cl I. Experimental Results

Abstract

Abstract Two Cu ++ centres in NH 4 Cl single crystals grown from acid (I) and neutral (II) aqueous solution were investigated by ESR and ENDOR at 4.2 °K. From the superhyperfine and quadrupole data obtained for several shells of neighbour nuclei the following centre models are proposed: in both centres Cu ++ is at an interstitial site with 2 NH 4 + vacancies along [001] at both sides of the Cu ++ . In centre I the vacancies are filled by H 2 O, in centre II by NH 3 . The precise configuration of the H 2 O and NH 3 molecules could be determined.