Nitrogen K-edge XANES - an overview of reference compounds used to identify unknown organic nitrogen in environmental samples.
The chemical nature of soil organic nitrogen (N) is still poorly understood and one-third to one-half of it is typically classified as ;unknown N'. Nitrogen K-edge XANES spectroscopy has been used to develop a systematic overview on spectral features of all major N functions in soil and environmental samples. The absolute calibration of the photon energy was completed using the 1s --> pi* transitions of pure gas-phase N(2). On this basis a library of spectral features is provided for mineral N, nitro N, amino acids, peptides, and substituted pyrroles, pyridines, imidazoles, pyrazoles, pyrazines, pyrimidines and purine bases. Although N XANES was previously considered ;non-destructive', effects of radiation damage were shown for two compound classes and an approach was proposed to minimize it. This new evidence is integrated into a proposal for the evaluation spectra from environmental samples with unknown composition. Thus a basis is laid to develop N K-edge XANES as a complementary standard research method to study the molecular composition and ecological functions of ;unknown N' in soil and the environment.
Leinweber
Peter
P
Institute for Land Use, University of Rostock, Justus von Liebig Weg 6, 18057 Rostock, Germany. peter.leinweber@uni-rostock.de
Kruse
Jens
J
Walley
Fran L
FL
Gillespie
Adam
A
Eckhardt
Kai Uwe
KU
Blyth
Robert I R
RI
Regier
Tom
T
D000596:Amino Acids / Q000032:analysis; D004785:Environmental Pollutants / Q000032:analysis*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000032:analysis; D009584:Nitrogen / Q000032:analysis*; D017672:Nitrogen Compounds / Q000032:analysis*; D012987:Soil / Q000032:analysis*; D013057:Spectrum Analysis; D014965:X-Rays
D000596:Amino Acids; D004785:Environmental Pollutants; D006576:Heterocyclic Compounds, 4 or More Rings; D017672:Nitrogen Compounds; D012987:Soil; D009584:Nitrogen