Trends in the Carbonyl Core (C 1S, O 1S) → π*_C=O Transition in the Near-Edge X-ray Absorption Fine Structure Spectra of Organic Molecules

Abstract

Carbonyl core (C 1s, O 1s) f π* CdO transitions are distinctive in the near-edge X-ray absorption fine structure (NEXAFS) spectra of species containing carbonyl groups. These features are used for the chemical microanalysis of organic materials using X-ray microscopy. We have explored the chemical sensitivity of these features in C 1s and O 1s NEXAFS spectra for a series of polymers containing the carbonyl group in a range of different bonding environments. Ab initio calculations are used to explain the origin of the observed trends and to explore the effect that orbital interactions have on the energy of these core (C 1s, O 1s) f π* CdO features. The differences between the experimental and the calculated carbonyl core (C 1s, O 1s) f π* CdO transition energies are systematic and can be used to develop a semiempirical method for predicting the absolute (experimental) transition energies from the calculated transition energies. This relationship is applied to a large body of calculated transition energy data to prepare correlation diagrams for the carbonyl (C 1s, O 1s) f π* CdO transitions. These correlation diagrams will be useful for the analytical application of NEXAFS spectroscopy to organic materials.

Oxygenated Interface on Biomass Burn Tar Balls Determined by Single Particle Scanning Transmission X-ray Microscopy

“…18,[20][21][22][25][26][27][28]30 Ketone CdO, carbonyl-substituted aromatic C, and phenolic C-OH can all have resonances at 286.7 eV. 22,25,30,31 Hence, an unambiguous assignment of this peak is not possible. However, as demonstrated below, combining the C-and O-edge spectra provides additional information about this transition.…”

Chemical composition of the graphitic black carbon fraction in riverine and marine sediments at sub-micron scales using carbon X-ray spectromicroscopy

“…Sedimentary environments along continental margins have a GBC fraction of BC which is characterized by more disordered graphite and amorphous carbon. The Equatorial Pacific GBC fraction is remarkable in the existence of highly-ordered graphite, but they also appear to contain significant aliphatic Hitchcock et al (1986Hitchcock et al ( , 1992, Hitchcock and Ishii (1987), Hitchcock and Stöhr (1987), Cody et al (1996Cody et al ( , 1998, Urquhart and Ade (2002), George Cody (pers. commun.…”

Long term effects of reduced fertilizer rates on millet yields and soil properties in the West-African Sahel

“…The beam line exit slit was set to 25 lm and partial fluorescence yield was collected using a silicon drift detector (AmpTek). The XANES spectral features for C and N types were identified from published diagnostic peaks of reference compounds (Leinweber et al 2010;Myneni 2002;Urquhart and Ade 2002). For C spectra, assignments were: (1) aromatic C at 285 eV; (2) ketone at 286.6 eV; (3) phenolic at 287.1 eV; (4) carboxylic at 288.6 eV; and (5) carbohydrate hydroxyl at 289.6 eV.…”