Measurement of spin-lattice relaxation times with longitudinal detection

New experimental schemes to measure spin-lattice relaxation times T-1 on th e basis of inversion-recovery and saturation-recovery experiments with long itudinal detection are introduced. With this approach, paramagnetic species with T-1 values as short as 20 ns can be measured. Possibilities to reduce unwanted signals and instrumental artifacts are analyzed. An experiment wh ere the signal is induced directly by the time-dependent M-2 magnetization is also proposed. Experimental results for organic radicals and defect cent ers are presented and compared with data obtained with conventional techniq ues, and a metal complex at 250 K is analyzed where it is very difficult to get information about relaxation times with established methods because of fast spin-spin relaxation.