Progressive saturation, spin lattice

A. Horska and R. G. Spencer, Measurement of spin-lattice relaxation times and kinetic rate constants in rat muscle using progressive partial saturation and steady-state saturation transfer. Magn. Reson. Med., 1996, 36, 233-240. 

C spin-lattice relaxation times of individual nuclei can also be measured by PFT 13C H experiments using a 90°, r, 90", r,... pulse train and noise modulation of the proton decoupling frequency. This method is known as progressive saturation [43] and is based on the following concept. 

Fig. 2.30. Determination of 13C spin-lattice relaxation times by inversion-recovery (a), progressive saturation (b), and comparative evaluation of the intensities (c) values from (a) with full, from (b) with empty characters, abscissa on top for C-2, abscissa on bottom for C-1 and C-3) sample propynol, 75% by vol. in hexadeuterioacetone. 25 C, not degassed, 15.08 MHz, 10 scans/ experiment in (a),...

The most commonly performed relaxation experiment is that of determining the spin-lattice relaxation time, 7, which is relatively easily measured by a variety of methods, such as inversion recovery30 or progressive saturation.31 All of these... 

The spin-lattice relaxation-time T, may also be measured by use of a 90°, f, 90° pulse sequence that employs decreasing values of f to produce a progressive saturation effect.173... 

R. Freeman and H. D. W. Hill, "Fourier transform study of NMR spin-lattice relaxation by progressive saturation, " J. Chem. Phys. 54, 3367-3377 (1971). 

Figure 8.2(c) is an inversion-recovery quadrupole echo pulse sequence, which is used to measure the Zeeman spin-lattice relaxation time,, with quadrupole echo detection [8,9,115]. Pre-saturation (Figure 8.2(d)) or progressive saturation (variation of the delay between transients) are also used to measure T. Notably, pre-saturation with spectral subtraction can separate the spectra of domains with different and is used to obtain the individual spectra of the amorphous and crystalline regions of semicrystalline polymers [8]. Also, Void and co-workers have recently presented methods involving selective inversion for the measurement of slow molecular reorientation, which provide an alternative to spin alignment or multidimensional methods [116]. 

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