A new Raman metric for the characterisation of graphene oxide and its derivatives

Raman spectroscopy is among the primary techniques for the characterisation of graphene materials, as it provides insights into the quality of measured graphenes including their structure and conductivity as well as the presence of dopants. However, our ability to draw conclusions based on such spectra is limited by a lack of understanding regarding the origins of the peaks. Consequently, traditional characterisation techniques, which estimate the quality of the graphene material using the intensity ratio between the D and the G peaks, are unreliable for both GO and rGO. Herein we reanalyse the Raman spectra of graphenes and show that traditional methods rely upon an apparent G peak which is in fact a superposition of the G and D' peaks. We use this understanding to develop a new Raman characterisation method for graphenes that considers the D' peak by using its overtone the 2D'. We demonstrate the superiority and consistency of this method for calculating the oxygen content of graphenes, and use the relationship between the D' peak and graphene quality to define three regimes. This has important implications for purification techniques because, once GO is reduced beyond a critical threshold, further reduction offers limited gain in conductivity.

Different complexation behavior of P-functionalized ferrocene derivatives towards SnCl2 , SnCl4 and SnPh2 Cl2 : auto-ionization and redox-type reactions

The novel phosphonyl-substituted ferrocene derivatives [Fe(η(5) -Cp)(η(5) -C5 H3 {P(O)(O-iPr)2 }2 -1,2)] (Fc(1,2) ) and [Fe{η(5) -C5 H4 P(O)(O-iPr)2 }2 ] (Fc(1,1') ) react with SnCl2 , SnCl4 , and SnPh2 Cl2 , giving the corresponding complexes [(Fc(1,2) )2 SnCl][SnCl3 ] (1), [{(Fc(1,1') )SnCl2 }n ] (2), [(Fc(1,1') )SnCl4 ] (3), [{(Fc(1,1') )SnPh2 Cl2 }n ] (4), and [(Fc(1,2) )SnCl4 ] (5), respectively. The compounds are characterized by elemental analyses, (1) H, (13) C, (31) P, (119) Sn NMR and IR spectroscopy, (31) P and (119) Sn CP-MAS NMR spectroscopy, cyclovoltammetry, electrospray ionization mass spectrometry, and single-crystal as well as powder X-ray diffraction analyses. The experimental work is accompanied by DFT calculations, which help to shed light on the origin for the different reaction behavior of Fc(1,1') and Fc(1,2) towards tin(II) chloride.

Has the Financial Services Reform Act fixed the problems with the regulation of securities and derivatives?

The Financial Services Reform Act 2001 (Cth) introduced new definitions of“derivative” and “financial product” into the Corporations Act 2001 (Cth), andreplaced the separate regulatory regimes governing futures contracts andsecurities with a single financial markets authorisation regime and a singleintermediary licensing regime. This article examines the reforms to evaluatewhether they have been successful. It is argued that there are definiteimprovements resulting from the reforms, and the scope for regulatoryarbitrage has been greatly reduced. However, numerous problems remain.There are significant differences in the regulation of securities and deriva-tives. The distinction between securities and derivatives is still based on legalcharacteristics, not economic function. There is uncertainty as to the exactscope and interaction of the definitions, particularly with respect to equityderivatives, warrants and options. The current law has thus not fullyaddressed many of the problems that existed prior to the reforms.