The inversion-recovery experiment allows to measure longitudinal or spin-lattice T₁ relaxation times of any nucleus.

Easy implementation on AVANCE spectrometers.

The basic pulse sequence of the inversion-recovery experiment consists of the following steps:

• A 180º pulse inverts the magnetization to the -z axis.
• During the following delay t, relaxation along the longitudinal plane takes place. Magnetization come back to the original equilibrium z-magnetization.
• A read 90º pulse creates transverse magnetization
• Acquisition is performed as usual

This procedure can be used to measure T₁ relaxation times of any nucleus. For instance, in the case of ¹³C, all pulses and acquisition are applied on ¹³C channel while broadband proton decoupling is applied during all sequence. A complete revision work about methods to measure T1 relaxation times has been appeared in 99CONC243

The Inversion-recovery experiment can be acquired, processed and plotted in a fully automated way. Minor changes from a predefined parameter set are required. Important parameters to consider are:

• Relaxation delay must be set to 5*T₁
• The experiment is repeated for a series of delays values.
• Rough estimation of the T₁ value from the null-point value by using T₁=t_null/ln(2). Quantitative analysis can be performed using the relaxation T₁ /T₂  software.

For further details on practical implementation of the inversion-recovery experiment on AVANCE spectrometers see:

• Tutorial: T1 1H measurements
• Tutorial: T1 13C measurements

The inversion-recovery experiment affords conventional 1D spectra. The signal intensities will shown a dependence with the interpulse t delay value:

• Using a short delay, all signals will shown negative intensities (aligned to -z axis)
• The intensity of the signals will decrease (will be less negative) when the delay is increased
• The null-point (t_null) is achieved when the corresponding signal is missing (intensity zero)
• Using longer delays, the signal intensities become positive.

See T1 Spectra

Related selective inversion-recovery experiments are efficient methods of measuring proton spin-lattice cross-relaxation rates in crowded regions ( 92MRC173 , 92JACS5412 , 93JB335 )