Pulse FT NMR of non-equilibrium states of half-integer spin quadrupolar nuclei in single crystals

Recent Advances in Solid-State 25Mg NMR Spectroscopy

“…86 The nutation behaviour following population distributions deviating from thermal equilibrium can be calculated numerically using the density operator formalism. 87,101 Thus, it is necessary to optimise the pulse length and the RF power for the CT excitation pulse(s) already with the populations changed by the adiabatic pulses.…”

“…The most commonly used are the quadrupolar Carr-Purcell-Meiboom-Gill (QCPMG) pulse sequence (based on multiple-pulse spin-echo methods) 36,74-76 and population transfer techniques such as rotor-assisted population transfer (RAPT), 77-80 double frequency sweeps (DFS) 81,82 and use of adiabatic inversion pulses, such as hyperbolic secant (HS) and WURST pulses. [83][84][85][86][87] There are several reviews and original papers about the theoretical and practical aspects involved in these methods. 74,76,84,86,[88][89][90][91][92][93][94][95] In this section, the principles underlying these approaches to signal enhancement are briefly revisited with reports of their applications to solid-state 25 Mg NMR experiments highlighted.…”

Numerical simulation of NQR/NMR: Applications in quantum computing

“…6b, which can be compared to the calculations and experimental results shown in Fig. 3 of reference [47]. A similar analysis can be performed for spin 5/2 nuclei, as done by Nakashima et al using 27 Al NMR measurements in a single crystal of Al 2 O 3 .…”

“…7 shows the result of our simulations, which can be directly compared to the calculations shown in Fig. 6 of reference [47]. The initial state was obtained by inversion of the populations of states jÀ5/2i and jÀ3/2i, followed by inversion of the populations of states jÀ3/2i and jÀ1/2i.…”

“…Another quite interesting example dealing with spin dynamics of quadrupolar nuclei in high-field NMR was provided very recently by Nakashima et al, who described the pulse response of half-integer spin quadrupolar nuclei in single crystals starting from general initial states (not necessarily corresponding to thermal equilibrium) [47]. This subject is of high interest considering the many sensitivity enhancement methods currently used for halfinteger spin quadrupolar nuclei that are based upon population transfers.…”