Decoupler mode

Selective saturation experiments were performed with the HX270 employing the homonuclear decoupling mode availcible with the instrument but substituting the usual situation by... 

Varian uses the decoupler mode (dm) parameter to determine when the decoupler should be turned on and off during the pulse sequence. Time periods A, B, C,. .. are defined during any pulse sequence, and the definition of these time periods can be observed by entering dps (display pulse sequence). For the general ID sequence called s2pul (simple 2-pulse), the periods A, B, and C are defined as follows ... 

These four decoupling modes along with their Bruker equivalents can be defined as follows ... 

Internally Decoupled Modes Intermediate Neglect of Differential Overlap (Approximation, Method)... 

Rigid and Relaxed Internal Hardness Decoupling Modes... 

Let us consider the intra-reactant decoupling, in which we rotate the AIM reference frame of M, feM, into the PNM of the mutually closed reactants, called the internally decoupled modes (IDM). If the relaxational influence of one reactant upon another is ignored, one readily obtains the rigid IDM by diagonalizing the reactant blocks of 9 (see Eq. (137)) ... 

Externally Decoupled Modes from the Maximum Overlap Criterion... 

Another, complementary set of partially decoupled populational modes is defined within the external hardness decoupling scheme [9, 45]. The externally decoupled mode (EDM) transformation, U xt= MUH, transforms the AIM hardness matrix if of the reactive system M+ = (A+ B+) into the block-... 

We therefore conclude that our algorithm for the IDM-localized externally decoupled modes, EDM (- IDM), does indeed generate reactive charge-displacement modes which can be easily correlated with both the IDM of reactants and the PNM of M as a whole. It follows from our illustrative results... 

Chemical shifts in ppm relative to external TMS. Data obtained with a Varian XL-100-15 spectrometer FT and decoupled mode (Mantsch and Smith, 1972). 

B) The effect of saturating the 2.338 resonance of the exo isomer at 37°C. Saturation is only transferred from the anti resonance of the exo isomer to the anti resonance of the syn isomer, demonstrating that rotation of the allyl is occurring. The data were collected in a gated decoupling mode i.e., the 2.338 resonance was irradiated for 10 seconds, the irradiation was terminated, and after a 0.1-second delay a 90° pulse was applied, followed by accumulation of the FID. 

Most NMR spectra are obtained in the simplified broadband decoupled mode first and then in modes that provide information from the couplings (Sections 9.1 ID... 

Q factors for the sum mode B and the vacuum states for the decoupled modes B2 3, we have the Mandel Q factors for the original cavity fields Q = Q3 = Q, Q2 Q- Correspondingly,... 

In practice, solution spectra (other than H) are usually run in /-decoupled mode, as will be discussed in Sec. III.D.3. This removes the scalar-coupling multiplicity, so that each resonance appears as a single peak. While this results in a less complicated spectrum, valuable clues to the molecular structure may be lost. In an attempt to regain this information, experiments have been devised which allow the J-couplings to be completely or partially restored without undue complication of the spectrum (Secs II.E.3 and II.E.4). 

In the hydrogen-decoupled mode, the sample is irradiated with two different radio frequencies. The first radio frequency is used to excite the C nuclei. The second is a broad spectrum of frequencies that causes all hydrogens in the molecule to undergo rapid transitions among their nuclear spin states. On the time scale of a C-NMR spectrum, each hydrogen is in a time average of the two states, with the... 

What would the Si NMR spectrum of the compound shown in Figure 4.27 look like, in coupled and decoupled modes ... 

For purposes of structure elucidation, it is generally not necessary to eliminate paramagnetic impurities since most spectra are obtained in the proton decoupled mode which is usually the source of signal broadening (M 31n). However, filtration of the sample solution may be advisable to avoid the field inhomogeneities arising from the fluctuation of small solid particles in the liquid. 

Alternatively, the sub-surface or bulk 0 species may diffuse to the surface to refill the vacancy. Note that only reactors operating in a redox decoupling mode, like CFBs, would derive oxygen from the bulk because the oxidation step is carried out in a distinct fluidized-bed reactor. Obviously this diffusion process is slower than the surface re-oxidation by molecular (gaseous) O2, but depending on the cation reducibihty during catalyst equilibration , part of the bulk becomes reduced. At the steady state (rR = rred = Tox) there is a hmited amount of 0 species able to participate in the reaction at each cycle (turn-over). 

Several theoretical attempts have been made recently to give a more complete description of the transport coefficients of mixtures in the critical region. Folk Moser (1993) performed dynamic renormalization-group calculations for binary mixtures near plait points and obtained nonasymptotic expressions for the kinetic coefficients. Kiselev Kulikov (1994) derived phenomenological crossover functions for the transport coefficients by factorizing the Kubo formulas for the transport coefficients a, p and y. This approach is referred to as the decoupled-mode approximation (Ferrell 1970). Their calculations yield for the thermal conductivity the expected finite enhancement in the asymptotic critical region and also a smooth crossover to the background far away from... 

Ferrell, R. A. (1970). Decoupled-mode dynanucal scaling theory of the binary-liquid phase transitions. Phys. Rev. Lett., 24, 1169-1172. 

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