Carbon emissions signature

Field emission from carbon nanotubes may be more complex than implied by the analysis above since, in contrast to metal tips, the Fermi wavelengths are comparable to the tip size and consequently electronic states exist, which extend over the entire tip [152,168]. Emission is therefore not from individual atoms but from these tip states such that the emission is coherent. The field emission patterns from individual MWNTs in fact carry the signature of coherent emission from the tip states [168] (see Fig. 36). SWNTs have been imaged as well and the patterns correspond with calculated nanotube charge densities [152]. 

SFS technique has been explored in the last years, e.g., to classify the composition of mixtures of heterogeneous CDOM present in natural freshwaters and in their different subtractions [27,28,33,34]. Similar attempts to identify certain structural and functional constituents in natural HMs have been carried out also with the aid of total luminescence spectroscopy [35]. At present, utilizations of fluorescence techniques are increasingly related to solve certain environmental questions, e.g., how does CDOM vary spatially between different aquatic environments/seasons, what is the causative factor for the leaching of natural carbons, are there any spectral signatures that could lead to the identification of CDOM sources In connection with the heterogeneity of CDOMs between different water samples there is no single spectral parameter that could explain the variation but chemometric applications are needed for interpretation of multidimensional excitation-emission matrices [33,35-39]. 

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