METHOD AND APPARATUS FOR LOCALLY RESOLVED INVESTIGATION OF A SPECIMEN

摘要

A method and an apparatus for a locally resolved investigation of a specimen, wherein the specimen is exposed to a constant magnetic field and a variable combination of three gradient magnetic fields directed substantially perpendicularly to each other and to a sequence of high-frequency (RF) pulses which contains three successive pulses with flip angles not equal to ¦m Pi¦, and signals corresponding to a magnetic resonance of spin moments, in particular nuclear spin moments in said specimen are detected. The interval (tau) between the first and the second pulse is greater than T2eff and smaller than 5T2, and that the interval (T-tau) between the second and the third pulse is greater than T2eff and smaller than 5T1, wherein m is an integer, T1 is the spin-lattice relaxation time, T2 is the spin-spin relaxation time and T2eff is the effective spin-spin relaxation time of the spins to be determined in the specimen. At least one of said gradient fields is switched between the first and/or the second pulse and/or the second and the third pulse and/or after the third pulse, wherein at least one of the RF pulses is a frequency-selective pulse and at least one echo signal stimulated by the third pulse is detected and evaluated.