Open AccessNitrogen K ‐edge XANES – an overview of reference compounds used to identify `unknown' organic nitrogen in environmental samples
Author(s) -
Leinweber Peter,
Kruse Jens,
Walley Fran L.,
Gillespie Adam,
Eckhardt KaiUwe,
Blyth Robert I. R.,
Regier Tom
Publication year - 2007
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049507042513
Subject(s) - xanes , nitrogen , chemistry , environmental chemistry , spectroscopy , analytical chemistry (journal) , organic chemistry , physics , quantum mechanics
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 1 s →π* 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.