ELECTRON-PARAMAGNETIC-RES OF MN-2+ DOPED AMMONIUM OXALATE MONOHYDRATE

X-band EPR studies on an Mn**2** plus -doped single crystal of ammonium oxalate monohydrate have been carried out at room, liquid nitrogen and liquid helium temperatures. The spin-Hamiltonian parameters are estimated using a recently-developed least-squares-fitting technique, especially adapted to electron-nuclear spin coupled systems. The absolute signs of parameters are determined from the relative intensity of lines at liquid-helium temperature. The data are used to determine the defect formation in the ammonium oxalate monohydrate lattice when Mn**2** plus ions substitute in it, thus resolving the presently existing controversy in the already-published results.