High resolution carbon spectra

Figure 5. X-ray photoelectron survey spectrum (a) of an o-phenylenedlamlne derlvatlzed glassy carbon surface. High resolution C Is and N Is spectra of a derlvatlzed surface (b) and surface which was derlvatlzed following reduction with lilAlH to destroy surface o-qulnone functional groups (c). The spectrum were signal averaged for 90 min (a) and 20 min (b and c) and smoothed prior to display.

To determine if alkylation had occurred on nonprotonated carbons, another high-resolution spectrum was obtained with the proton decoupler turned off. The two CD3 resonances remained broad the peak at 8 36 and... 

Figure 14 Carbon Is high-resolution ESCA spectrum of control hair (A) and hair treated (30 min) with 0.1% Polymer JR 400 (B) and 0.1% Quatrisofl LM 200 (C) solutions. (From Ref 20.)... 

A useful method to correlate IH and 13C signals is wide-line separation In a two-dimensional (2D) spectrum high-resolution 13C CP MAS spectra are taken in one dimension, and correlated to the IH wide-line spectra of the protons attached to each resolvable carbon atom. This enables the correlation between the IH mobility, as detected by the linewidth, and the 13C structure viewed by the chemical shifts. 

The C NMR spectrum of the metabolite shows 16 signals instead of 8 as expected from the elemental composition determined by high-resolution mass spectrometry. Moreover, aromaticity of the 2,6-xylenol is obviously lost after metabolism because two ketonic carbonyl carbon atoms (5c = 203.1 and 214.4) and four instead of twelve carbon signals are observed in the shift range of trigonal carbon nuclei (5c = 133.1, 135.4, 135.6 and 139.4) in the C NMR spectra. To conclude, metabolism involves oxidation of the benzenoid ring. 

The XPS survey spectrum of a 75 nm thick film of plasma polymerized acetylene that was deposited onto a polished steel substrate is shown in Fig. 18 [22]. This film consisted mostly of carbon and a small amount of oxygen. Thus, the main peaks in the spectrum were attributed to C(ls) electrons near 284.6 eV and 0(ls) electrons near 533.2 eV. Additional weak peaks due to X-ray-induced O(KVV) and C(KLL) Auger electrons were also observed. High-resolution C(ls) and 0(ls) spectra are shown in Fig. 19. The C(ls) peak was highly symmetric. 

The 5 Hz optimized l,n-ADEQUATE spectrum of strychnine (1) is shown in Figure 9.70 The high resolution 600 MHz proton spectrum is shown in Figure 10A and compared to slices extracted at the Fi frequency of the C15 methylene resonance in the 5 Hz optimized l,n-ADEQUATE spectrum (B) and the 60 Hz optimized 1,1-ADEQUATE spectrum (C). The adjacent carbons (via Vcc) show correlations in the 5 Hz optimized INADEQUATE spectrum that are unsuppressed but all possible three-bond... 

We have selected several unblended CH lines located in the near-UV between 3145-3190 A modified their oscillator strengths (gf-values) by fitting the solar high-resolution spectrum and assuming solar abundance of carbon 8.56 from Anders and Grevesse (1989). These lines are measurable in dwarfs down to the metallicities —3. Our results are shown in the Fig. 1. We confirm the metallicity dependence of the C/O ratio (Tomkin et al. 1992, Akerman et al. 2004). On the other hand, our plot for C/O shows a steep rise at [0/H]< —1. It is not clear if this effect is real. The work is in progress to address this issue using other abundance indicators such as CH 4300 A and better quality spectra. 

The additional detail provided by a high resolution spectrum allows more information to be determined about the structure of the compound. Analysing the multiplets allows the neighbouring proton environment to be identified. This can be done using the n + 1 rule, where n is the number of carbon atoms attached to the next-door carbon atom and n + 1 is the number of peaks that will be seen in the cluster. 

Owing to the differences in both the nature and magnitude of the homo-and hetero-nuclear dipolar interactions, the process of eliminating the dipolar interactions to obtain a high resolution spectrum in the solid state is slightly different for protons and carbons, respectively, and will be reviewed separately in following... 

XPS spectra obtained on the uncoated dolomite sample (Figure 2) showed the presence of carbon, oxygen, and calcium, as would be expected for a calcium carbonate material. Traces of chlorine, probably present as precipitated salts were also observed by electron microprobe analysis in previous studies 4). The high-resolution C Is spectrum, however, showed that carbon was present in at least three different chemical states (Figure 2, inset). The peak occurring at a BE of 284.3 eV is consistent with the presence of adventitious hydrocarbon... 

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