Nutation

For quadnipolar nuclei, the dependence of the pulse response on Vq/v has led to the development of quadnipolar nutation, which is a two-dimensional (2D) NMR experiment. The principle of 2D experiments is that a series of FIDs are acquired as a fimction of a second time parameter (e.g. here the pulse lengdi applied). A double Fourier transfomiation can then be carried out to give a 2D data set (FI, F2). For quadnipolar nuclei while the pulse is on the experiment is effectively being carried out at low field with the spin states detemiined by the quadnipolar interaction. In the limits Vq v the pulse response lies at v and... 

The low MW power levels conuuonly employed in TREPR spectroscopy do not require any precautions to avoid detector overload and, therefore, the fiill time development of the transient magnetization is obtained undiminished by any MW detection deadtime. (3) Standard CW EPR equipment can be used for TREPR requiring only moderate efforts to adapt the MW detection part of the spectrometer for the observation of the transient response to a pulsed light excitation with high time resolution. (4) TREPR spectroscopy proved to be a suitable teclmique for observing a variety of spin coherence phenomena, such as transient nutations [16], quantum beats [17] and nuclear modulations [18], that have been usefi.il to interpret EPR data on light-mduced spm-correlated radical pairs. 

Furrer R, Fujara F, Lange C, Stehlik D, Vieth H and Vollmann W 1980 Transient ESR nutation signals in excited aromatic triplet states Chem. Rhys. Lett. 75 332-9... 

Figure Bl.16.15. TREPR spectmm after laser flash photolysis of 0.005 M DMPA (5) in toluene, (a) 0.7 ps, 203 K, RE power 10 mW O, lines CH (8), spacing 22.8 G , benzoyl (6), remaining lines due to (7). (b) 2.54 ps, 298 K, RE power 2 mW to avoid nutations, lines of 7 only. Reprinted from [42].

BittI R, van der Est A, Kamlowski A, Lubitz W and Stehlik D 1994 Time-resolved EPR of the radical pair bacterial reaction centers. Observation of transient nutations, quantum beats and... 

NutraSweet Nutricote Nutrient removal Nutrients Nutrients, trace Nutation... 

Nuclear electric quadrupole QCC (quadrupole coupling constant), (asymmetry parameter) Line-shape analysis, nutation NMR Coordination symmetry... 

Nutation. The axis of a spin-stabilized projectile in flight is subject to spasmodic small conical vibrations, called nutation, which should not be confused with yaw (qv) or precession (qv). The instant a spinning projectile leaves a gun, the turbulence produced by the release of proplnt gases causes nutations to occur. Their amplitude is usually small, and, in the case of concentric fast spinning projectiles, they disappear due to the action of equal and opposite centrifugal forces. 

If the projectile spin is insufficient, the amplitude of the nutations increases, soon causing the projectile to tumble in flight Refs 1) R. d AdhSmar, Sur le Mouvement Pendulaire des Projectiles Stables , MAF 8, 3rd fasc (1929) Ibid 9 3rd fasc (1932) Ibid 12,... 

Fig. 2 (a) DRAMA pulse sequence (using % = t/2 = rr/4 in the text) and a representative calculated dipolar recoupled frequency domain spectrum (reproduced from [23] with permission), (b) RFDR pulse sequence inserted as mixing block in a 2D 13C-13C chemical shift correlation experiment, along with an experimental spectrum of 13C-labeled alanine (reproduced from [24] with permission), (c) Rotational resonance inversion sequence along with an n = 3 rotational resonance differential dephasing curve for 13C-labeled alanine (reproduced from [21] with permission), (d) Double-quantum HORROR experiment along with a 2D HORROR nutation spectrum of 13C2-2,3-L-alanine (reproduced from [26] with permission)... 

The analytic evaluation of the density matrix requires the diagonalization of Hi, which can be easily performed for the two extreme cases, a>r( Qg. Indeed, in the case of a low rf-field, only off-diagonal terms related to the CT are retained in the H Hamiltonian (39), which thus behaves like a fictitious spin-1/2 operator, affecting only the CT coherences /1 io- These coherences are thus selectively excited with the nutation frequency ... 

When fflrf Qg, the excitation becomes non-selective and thus all spin states develop coherences. The resulting transverse magnetization nutates with the... 

The spin-locking and CP behavior of the most commonly used SQ coherence (CT) in quadrupolar nuclei under static and MAS conditions has been described in detail by Vega using the fictitious spin-1/2 approximation [223]. In a static sample, the Hartmann-Hahn matching condition requires that co = nut where co ut is one of the nutation frequencies associated with the SQ coherence of the quadrupolar S spin (see Sect. 2.3.4). In the simple case of on-resonance SQ-CP this translates to [224]... 

The Hartmann-Hahn MQ-CP transfer can be achieved when the rf frequency of spin I in the rotating frame is sufficiently close to one of the SQ or MQ nutation frequencies of spin S, co/ut = oJlf. In the case O/ > co/f, the nutation frequency for a symmetric MQ coherence of order p is given by [222, 229]... 

Many chemically-synthesized GaN samples exhibit a peak from the dominant WZ form, and a much smaller peak from the ZB form. Because of the good resolution, sensitivity, and dynamic range of 71Ga MAS-NMR, polymorphs present at levels below the detection sensitivity of XRPD of 1% could be identified. Quantitation needs to take into account the differing nutation behavior (mentioned in Sect. 3.2.1 in terms of effective 90° pulse lengths) of the ZB and WZ 71Ga peaks. 

Disk filters, 11 374-377 16 658. See also Rotary disk vacuum filters Disk flat blade turbine, 16 701 Disk meters, nutating, 11 655 Disk pumps, 21 69 Dislocation density, 13 496 Disodium 5 -guanylate (GMP), 12 49 Disodium 5 -inosinate (IMP), 12 49 Disodium acetylide, 22 765 Disodium cocoamphodiacetate, cosmetic surfactant, 7 834t Disodium decacarbonyldichromide, 6 528-529... 

Nutating disk meters, 11 655 Nutmeg, 23 155, 168 Nutraceutical activities, classification of, 17 647... 

The excitation profile of multiple bands was also known for periodic RF pulses, such as the DANTE (delays alternating with nutation for tailored excitation) sequence.26 Similar to the PIP, all the phases and strengths of the effective RF fields can be obtained by expanding the periodic pulse into a Fourier series and properly rearranging the terms afterwards.27 Detailed calculation, comparison with the PIP, and the excitation profiles by a periodic pulse of fix sin(7tt/T) Ix and a DANTE sequence are presented in Section 3. 

NMR properties, 33 213, 274 in nutation-NMR spectroscopy, 33 333 in sheer silicate smdies of, 33 340-341 layer structure, 32 184-186 on metal surfaces, 32 194-197 model, oscillatory reactions, 39 97-98 number... 

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