ENDOR studies on the W7 di-nitrogen centre in brown diamond

Abstract

A new technique, involved rapid and repeated sweeping of radio-frequency irradiation through a wide frequency range, has been used to enhance the ENDOR signal of the W7 di-nitrogen centre in diamond. This allowed the determination of the following magnetic hyperfine and electric quadrupole interaction parameters (expressed in MHz) for the two nitrogen atoms: A/sub ///(1)=121.39(3), Aperpendicular to (1)=86.00(3), PA/sub ///(1)=2.55(3), Pperpendicular to (1)=1.27(3), A1(2)=13.58(5), A2(2)=16.01(5), A3(2)=14.00(5), P1(2)=0.13(1), P2(2)=-0.13(1), P3(2)=0.000(5). The interactions for A(1) and P(1) are axially symmetrical about 111, but those for A(2) and P(2) have low symmetry, and their principal axes have no clear relationship with one another or with the crystal structure. Hence, the overall symmetry of the site is established as C1.