Abstract: The L-histidine copper(11) complex is one of the important components of thecopper-proteins. The electron paramagnetic resonance (EPR) Studies of C_x²⁺ located in the L-histidine C_u²⁺ complexes is very important for understandingthe processes of physiology and biochemistry related to the copper-proteins. In this article EPR technique has been used to study C_u²⁺ doped L-histidine single crystals at 4.2K. The EPR spectra of C_u²⁺ doped in single crystal of L-hisitidine hydrochloride monohydrate indicates that the C_x²⁺ ion is incorporated in a different environment from that in the ordinary L-histidine C_x²⁺ complex.
The ground state of C_u²⁺ doped L-histidine single crystal is a kramer's doublet state. The coefficients of this doublet state were determined from the observed g tenson and in such a way that the hyperfine coupling parameters of C_x²⁺ ion were calculated from these coefficients and a satisfactory agreement has been obtained between the calculated and the observed values.