Carbon-1 3 high-resolution

PEEK on Copper(II). In contrast to the PEEK on Cu(I), PEEK on Cu(II) did not significantly change in composition from 100-250 C. Between 250 C and 300 C, an abrupt compositional change was noted. This change was marked by a large increase in Cu(I) and the disappearance of carbon. High resolution ESCA spectra suggest that there is a sharp reduction of Cu(II) and the desorption and/or decomposition of PEEK above 250 C. 

Breitmaier E and Voelter W 1986 Carbon-13 NMR Spectroscopy High Resolution Methods and Applications in Organic Chemistry (New York VCH)... 

Figure Bl.13.4. The inversion-recovery detennination of the carbon-13 spin-lattice relaxation rates in melezitose. (Reproduced by pemiission of Elsevier from Kowalewski J and Maler L 1997 Methods for Structure Elucidation by High-Resolution N R ed Gy Batta, K E Kover and Cs Szantay (Amsterdam Elsevier) pp 325-47.)...

Fig. 2. High resolution (3, 000, OOOx ) electron micrograph of H-300-grade carbon black.

The degradation of 2,6-xylenol (2,6-dimethylphenol) by bacteria produces a metabolite with elemental composition C8///0O2 as determined by high-resolution mass spectrometry Which carbon skeleton and which relative configuration are deducible from the NMR experiments 44, all obtained from one 1.5 mg sample ... 

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 photoelectron line of main interest is Cls. Different bonding in the environments of the carbon atoms leads to very small chemical shifts of this line. High-resolution XPS is, therefore, required and monochromatic radiation should be used to prevent overlap with satellite lines. 

Regarding a historical perspective on carbon nanotubes, very small diameter (less than 10 nm) carbon filaments were observed in the 1970 s through synthesis of vapor grown carbon fibers prepared by the decomposition of benzene at 1100°C in the presence of Fe catalyst particles of 10 nm diameter [11, 12]. However, no detailed systematic studies of such very thin filaments were reported in these early years, and it was not until lijima s observation of carbon nanotubes by high resolution transmission electron microscopy (HRTEM) that the carbon nanotube field was seriously launched. A direct stimulus to the systematic study of carbon filaments of very small diameters came from the discovery of fullerenes by Kroto, Smalley, and coworkers [1], The realization that the terminations of the carbon nanotubes were fullerene-like caps or hemispheres explained why the smallest diameter carbon nanotube observed would be the same as the diameter of the Ceo molecule, though theoretical predictions suggest that nanotubes arc more stable than fullerenes of the same radius [13]. The lijima observation heralded the entry of many scientists into the field of carbon nanotubes, stimulated especially by the un-... 

The earliest observations of carbon nanotubes with very small (nanometer) diameters [151, 158, 159] are shown in Fig. 14. Here we see results of high resolution transmission electron microscopy (TEM) measurements, providing evidence for m-long multi-layer carbon nanotubes, with cross-sections showing several concentric coaxial nanotubes and a hollow core. One nanotube has... 

Fig. 14. High resolution TEM observations of three multi-wall carbon nanotubes with N concentric carbon nanotubes with various outer diameters do (a) N = 5, do = 6.7 nm, (b) N = 2, do = 5.5 nm, and (c) N = 7, do = 6.5 nm. The inner diameter of (c) is d = 2.3 nm. Each cylindrical shell is described by its own diameter and chiral angle [151].

Fig. 26. High-resolution TEM images of bent and twisted carbon nanotubes. The length scales for these images are indicated [199].

Oshida, K., Kogiso, K., Matsubayashi, K., Takeuchi, K., Kobayashi, S., Endo, M., Dressclhaus, M. S., Drcsselhaus, G., Analysis of pore structure of activated carbon fibers using high resolution transmission electron microscopy and image processing, 7. Mater. Res., 1995, 10(10), 2507 2517. 

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. 

Key Words—Carbon nanotubes, vapor-grown carbon fibers, high-resolution transmission electron microscope, graphite structure, nanotube growth mechanism, toroidal network. 

Carbon tubules (or nanotubes) are a new form of elemental carbon recently isolated from the soot obtained during the arc-discharge synthesis of fuller-enes[I]. High-resolution electron micrographs do not favor a scroll-like heUcal structure, but rather concentric tubular shells of 2 to 50 layers, with tips closed by curved, cone-shaped, or even polygonal caps. Later work[2] has shown the possibility of obtaining singleshell seamless nanotubes. 

Fig. 3. High-resolution electron micrograph (HREM) of oxidised CNT tips. Note the amorphous carbon residue inside the lower nanotube (marked with an arrow).

H. Daimon and Y. Hirata, Direct coupling of capillary supercritical fluid chromatography with superaitical fluid extraction using modified carbon dioxide , J. High Resolut. Chromatogr. 17 809-813 (1994). 

Figure 2. High-resolution transmission electron micrograps of carbon black (Sterling R, Cabot Corp.) (a) as-received (b) heat-treated at 2700 °C. Scale marker 10 nm.

Two possibilities for the observed enriched values for many of the grazers, and the often concomitant but slight enrichment of browsers (Fig. 5.6), present themselves. Either these shifts represent atmospheric CO2 enrichment shifts at particular periods during the last -lOOKa represented (the Late Pleistocene), or a hitherto unknown or unrecognized fractionation process has taken place during burial and fossilization. The former hypothesis could be tested by comparison of observations from a larger sample set from the site, with CO2 concentration and carbon isotope data from Antarctic ice-core records or high resolution marine isotope records. 

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