ESR spectra of Cu3(2A1) in an N2 matrix

ESR spectra assigned to 63Cu3 molecules have been obtained by codepositing atomic copper with excess nitrogen and then annealing to 25-30 K. The spectra extend over a 4000-G field range and are characterized by an orthorhombic g tensor with principal values 2.0042 (15), 1.9905 (15), and 1.9769 (15). The hf interaction is nearly isotropic. Powder pattern line shapes were simulated by using an elliptic integral algorithm which allowed an assignment of the trimer principal axes transitions. Magnetic parameters were obtained from a simplex least-squares algorithm and numerical diagonalization of the spin Hamiltonian at the observed transition fields. Measured isotropic spin populations are rho/sub 4s/ = 0.359 (1) and rho/sub 4s/ = 0.128 (1) on the unique apical and two (nearly) equivalent basal nuclei, respectively. The ESR spectra determine a localized, acute angled trimer (2A1 ground state) for Cu3 in nitrogen matrices