Inter-echo time

T2 maps were obtain fiom multi spin echo (MSE) images with 32 consecutive echoes, 30 ms inter-echo time and TR=10 s. Ti maps were measured using the TOMROP sequence with 32 consecutive echoes, Tl=210 ms and TR=10 s. T2 and T maps were calculated on a pixel-by-pixel basis using corresponding monoexponential fimctions, via the Levenberg-Marquardt criterion for chi-square minimization... 

TE—inter-echo time the time between the n pulses and identical to the time between two echoes. 

In most logging tools, the wait time, TW, and the inter-echo time, TE, are the key acquisition parameters to probe the hydrocarbon fluid properties (Georgi and Chen, 2007). 

A uniform modulation of the gradient vector leads to a waveform G(t), where inter-dispersed 180° pulses invert the sign of prior gradients. Provided that one is dealing with molecular spin motion in which sudden local phase changes are avoided, it is possible to show that the phase distribution of the magnetization components exposed to such a motion is Gaussian in character and that the normalized echo attenuation at time t may be written as... 

The principal relaxation times measurable for resolved resonances from solution state samples are the spin-lattice relaxation time (T ) and the spin-spin relaxation time (T2). Spin echo methods may be used to measure T2 values and these are often useful in defining chemical exchange rate processes. values are readily obtained from the inversion-recovery experiment and can be directly used to provide structural information. For nuclei with spin I = 1/2 in diamagnetic molecules in solution there are two principal mechanisms which contribute to the rate of the relaxation namely the dipole-dipole inter-... 

Due to the trace division procedure, the noise in the resulting RE time trace (Fig. 7(B)) is growing towards long times, therefore data with good SNR are essential for proper distance extraction. On the other hand, detection in inversion recovery experiment can be done with very short inter-pulse delay, only limited by the dead time of the spectrometer, which makes the detected echo much stronger than in a DEER experiment. At X band, where RE-based distance measurements were mainly performed so far, the concentration sensitivity of RE technique seems to be somewhat better that the one of DEER. ° ... 

Another class of methods measures inter-spin dipolar interactions using pulses that selectively manipulate different spin populations. The representative of this class, which is widely used in SDSL, is double electron-electron resonance (DEER, also known as PELDOR, Fig. 6). In the dead-time free DEER scheme, a three-pulse sequence is applied to the observer spin (spin A) to generate a refocused echo at a specific... 

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