Saturate fingerprints

Fig. 2e), virtually absent in perfect siUcalite-1 and immediately identified as a fingerprint of TS-1 material [37,52-55,63,70,71]. A qualitative correlation between the intensity of the infrared band at 960 cm and Ti content has been observed since the first synthesis of TS-1. Indeed, the occurrence of that band is one of the distinctive features of the material cited in the original patent [7]. However, the quantitative correlation has been reported only very recently by Ricchiardi et al. [52], owing to very serious experimental problems related to the saturation of the IR framework modes, hi the same work, the nature of the 960 cm band has been discussed in terms of theoretical calculations based on both cluster and periodical approaches. 

In addition to molecular weight, percentage saturation of the standard Daylight fingerprint has been used to describe the degree of molecular functionality [78]. Compounds with saturation outside a certain range (e.g., <10% and >60% saturation) can be excluded in order to remove overly simple or complicated molecules that would otherwise pass a simple molecular weight cutoff. 

It is well known for example in the saturated LDPE polymer chains that a certain number of double bounds exist which can be measured with IR spectroscopy. By extraction with non-polar solvents and GC separation, numerous alkanes and alkenes can be identified which are dissolved in small concentrations in the PE. The odor thresholds of these compounds are in general so high that these hydrocarbons play no sensory role. As a result no correlation can be made between the total amount of volatile compounds isolated from PE or the fingerprint chromatogram from a GC separation and the sensory properties of a sample. The relevant sensory compounds as a rule are the (order of magnitude) less concentrated oxygenated compounds in the... 

The atmospheric noble gases are presented in Fig. 13.5 in a fingerprint diagram. An overall similarity of the line patterns to those of air-saturated water at 15-25 °C is clear. Thus the relative abundances of the four noble... 

Hydrocarbon Based Polymers. The substitution of one hydrogen atom in the -CH2-CH2- unit by some short carbon chains induces subtle modifications in the electronic structure (molecular orbitals) of the polymers. Though these modifications cannot be easily evidenced on the XPS carbon Is core level spectra, it appears that the XPS valence band structures are much more sensitive to these substitutions and that they become unique and readable fingerprints of the polymers (1, 22). We will not speak here of the Cls shake-up data that were revealed useful to distinguish between saturated and unsaturated bonds (this field with various applications was recently reviewed (23)). 

Pulse radiolytic experiments with Cso in nitrogen-saturated or aerated DCE solutions yielded a doublet with maxima at 960 and 980 nm [64, 65]. This fingerprint is identical with that computed in CNDO/S calculations [66]. Because of the shortlived nature of the [DCE] + radical, the rate constants for the Ceo oxidation could only be estimated values were ca 2 x 10 m s [64, 65]. 

Figure 5a. GLC fingerprints of Kuwait crude saturates (total saturates, normal and nonnormal paraffins)...

PAH compounds are probably the most studied hydrocarbon group in crude oils and refined products. Crude oils and refined products from different sources can have very different PAH distributions. In addition, many PAH compounds are more resistant to weathering than their saturated hydrocarbon counterparts (fx-alkanes and isoprenoids) and volatile alkylbenzene compounds, thus making PAHs one of the most valuable fingerprinting classes of hydrocarbons... 

We assume that (i) the 960 cm band does not saturate for the TS-1 sample with lowest Ti content and (ii) the true Full Width at Half Maximum (FWHM) of this band is constant over all set of TS-1 samples. The former assumption is supported by the fact that the intensity of the 960 cm band, for the x = 1.0 sample, is less than 1.5 in absorbance units, while the latter is exactly what expected for a band associated to different concentrations of a unique species. Assumption (i) allows us to measure the true FWHM of the 960 cm band in TS-1 samples (27 cm ). Now, following assumption (ii), we were able to estimate for all samples reported in Fig. 3, the absorbance (W) at the height where the width of the band corresponds to 27 cm. This method minimize the errors due to the instrument sensibility and allows a quantitative estimation of the band intensity. Such obtained values plotted against x in the Fig. 3d ( data), give a high linear correlation (r = 0.9998) and validate assumption (i) and (ii). A further, and definitive, validation comes from the similar linearity found for the intensities of the Raman band, which can not be affected by saturation problems, see Fig. 3d ( data). These results implies that the 960 cm band is well a fingerprint of the insertion of Ti in the zeolitic framework, even if not... 

Oxidation The radiation-chemically induced ionization of chlorinated hydrocarbons, i.e., dichloroethane (DCE) leads to the initial generation of the corresponding solvent radical cation, [DCE] ". The electron affinity of the latter is sufficient to oxidize the fullerene moiety ([60]fullerene E1/2 = +1.26 versus Fc / Fc ). Pulse radiolytic experiments with [60]fullerene in nitrogen-saturated or aerated DCM solutions yielded a doublet with maxima at 960 and 980 nm (Figure 1) (12-18). This fingerprint is identical to that detected in photolytic oxidation experiments and that computed in CNDO/S calculations. Rate constants for the [60]fullerene oxidation are typically very fast with estimated values IC7 > 2 x 10 ° M s. The 7t-radical cation is short-lived and decays via a concentration-dependent bimolecular dimerization reaction with a ground state molecule (kg = 6 x lO M s ) (13). 

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