EXTENSION OF THE RORSCHACH-HAZLEWOOD THEORETICAL-MODEL FOR SPIN-LATTICE RELAXATION IN BIOLOGICAL-SYSTEMS TO LOW-FREQUENCIES

The water-biopolymer cross-relaxation model, proposed by H. E. Rorscha ch and C. F. Hazlewood (RH) [J. Magn. Reson. 70, 79 (1986)], explains the Larmor frequency dependence of T-1 in many biological systems. How ever, the RH theory fails at low Larmor frequencies, In this paper, a more general version of the RH theory has been developed. This theory is valid at all frequencies. Use of the new expression for the spin-la ttice relaxation rate (1/T-1), earlier published experimental data in H2O/D2O bovine serum albumin, which had been measured over a wide freq uency range (10 kHz to 100 MHz), were fitted over the entire frequency range, The agreement between theory and the experimental data is exce llent, Theoretical expressions for the rotating-frame spin-lattice rel axation rate (1/T-1 rho) were also obtained. (C) 1996 Academic Press, Inc.