Off-resonance spectra

C NMR spectrum The 13C NMR spectrum of parbendazole is shown in Fig. 5.5 (full 13C NMR spectrum) and Fig. 5.6 (off-resonance spectrum). 13C chemical shift data in TFA-d, are summarized in Table 5.5, which are consistent with the 13C contents of parbendazole. The assignments for the observed bands are based on established chemical shift parameters, off-resonance spectra, and comparisons with the following... 

The C-NMR noise-decoupled and off-resonance spectra (Fig. 6 and T)5 were recorded over 5000 Hz width in CDC1 on Varian FT.80, 80 MHz NMR spectrometer, using a 10 mm sample tube and TMS as a reference standard at 20°. 

The carbon-13 NMR completely decoupled and off-resonance spectra are shown in Fig. 3 and 4 respectively. 

The C-NMR noise decoupled and off resonance spectra are presented in Fig. 2 and Fig. 3 respectively. Both were recorded over 1+000 Hz range in deuterated chloroform on a Varian FT80 A-80 MHz spectrometer, using 10 mm. sample tube and tetramethyl silane... 

In alkaloids such as isocorydine (57) and bulbocapnine (58), which contain substituents on C-10 and C-11, the chemical shifts of the ring D carbon atoms were determined not only by the methods discussed above but also by the observation of second-order effects in the off-resonance spectra of C-8 and... 

The most widely used method for determining multiplicities of carbon atoms is DEPT (Distortionless Enhancement by Polarization Transfer). This has generally replaced the classical method of recording off-resonance spectra with reduced CH couplings from which the multiplicity could be read directly. 

In a 1 5 mixture of SbFj SOjClF at -20°C ds-3-chlorobicyclo[3,l,0]hexane gave a carbonium ion whose and n.m.r. were recorded. In the spectrum two absorptions at S 4.7 and 17.3 gave a doublet and a singlet respectively in the off-resonance spectra. The high-field absorption was associated with a — 196 Hz, and the low-field signal with /i3c h = 168 Hz. These data, together with the absence of hydride shift which frequently occurs at — 130 C for unstabilized cations, are consistent (within the limits of the n.m.r. time scale) with formulation of the carbonium ion as (376). 

In fig. 19 results for the valence PES spectra of the Ce pnictides are shown (Gunnarsson and Schonhammer 1985b). The off-resonance spectra of the pnictides show spectra with a peak at — 2eV. For simplicity we have therefore used a simple triangular shape for V eY as shown in the insert. The figure shows results for both U = CO and for a finite U. In this case the finite U effects have a small influence on the spectra. The weight of the Kondo peak is also negligible. In these cases the hybridization effects dominate. The same conclusion was reached by Sakai et al. (1984). 

Fig. 30. 4f contribution to the photoelectron spectra of a series of Ce-based compounds. All these spectra were taken on the same instrument and the background of scattered electrons subtracted in the same fashion. These spectra are the difference between on-resonance and off-resonance spectra. They are ordered by increasing amount of 4f-valence electron hybridization from the bottom to the top (mote 7-Ce-like to more a-Uke). (After Allen et al 1986.)... 

As mentioned already, the INEPT spectra are typified by the antiphase character of the individual multiplets. The INEPT C-NMR spectrum of 1,2-dibromobutane is shown, along with the normal off-resonance C-NMR spectrum, in Fig. 2.12. Doublets show one peak with positive phase and the other with negative phase. Triplets show the outer two peaks with positive and negative amplitudes and the central peak with a weak positive amplitude. Quartets have the first two peaks with positive amplitudes and the remaining two peaks with negative amplitudes. 

How can spectral editing in INEPT be used to generate separate spectra for CH, CH2, and CH3 groups, and how is it superior to the traditional off-resonance decoupled spectra ... 

A spontaneous Raman spectra is shown in Figure 2.8d in which the on- and off-resonant frequencies are indicated. The DNA bundles are observed at the resonant frequency, as shown in Figure 2.8a, while they cannot be seen at the off-resonant frequency in Figure 2.8b. This indicates that the observed contrast is dominated by the vibrationally resonant CARS signals. Figure 2.8c shows a cross-section of Figure 2.8a denoted by two solid arrows, which were acquired with a 5 nm step. The FWHM of... 

In the study of 13C-NMR spectra of 8 and 6, the presence of the hydroxyl group at C-14 is also evident since a downfield shift of 43 ppm from 6 (<521.2) to 8 (<563.87) is observed. The previously ambiguous assignments of C-15, C-16, C-5, and C-20 are also clarified through irradiation of H-16, H-5, and H-20 with low-power single-frequency off-resonance decoupling (SFORD) experiments. 

Figure 7. Light scattering of a microresonator with a water cladding (a) spectra obtained as response to a tunable laser with clearly visible high finesse resonances (b) CCD camera images of the microresonator obtained off-resonance, (c) idem on-resonance.

Proton-noise decoupled and single-frequency off-resonance decoupled carbon-13 NMR spectra were determined for the CTC Working Standard (Figure 13). 

Fig. 16. Cross-relaxation or Z-spectra derived from the solvent proton spectra of cross-linked bovine serum albumin gel supported in a ternary solvent system consisting of 8.8% H2O, 8.7% acetone, and 8.8% methanol and 63% D20.The offset axis represents the frequency offset of the off-resonance preparation pulse which partly saturates the immobilized spin. In this case the 3 s preparation had an amplitude of 880 Hz at a Larmor frequency of 500 MHz (87).

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