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Iterative Least‐Squares Lineshape Fitting of 1 H‐decoupled 13 C‐DNMR.Spectra
Author(s) -
Heinzer Josef,
Oth Jean F. M.
Publication year - 1981
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19810640127
Subject(s) - chemistry , spectral line , least squares function approximation , relaxation (psychology) , kinetic energy , line (geometry) , nmr spectra database , population , position (finance) , nuclear magnetic resonance , analytical chemistry (journal) , molecular physics , physics , statistics , quantum mechanics , chromatography , psychology , geometry , mathematics , demography , estimator , sociology , finance , economics , social psychology
Iterative least‐squares lineshape fitting of 1 H‐decoupled 13 C‐DNMR. spectra is advantageously used for the investigation of symmetrical or asymmetrical intramolecular (two‐structure) exchange processes. The least‐squares procedure adopted allows the following parameters to be either optimized by computer or kept constant (according to experimental conditions): the nuclei populations (taking into account line intensity effects resulting from differences in spin‐lattice relaxation times and/or Overhauser enhancements), the corresponding chemical shifts and natural linewidths (characterizing the sites undergoing exchange), the fractional population of one structure (in the case of asymmetrical exchange), one of the chemical rates, the base‐line position, and the base‐line tilt. The relative sensitivity of the lineshape with respect to the fitted parameters as well as the importance of correlations among these parameters have been investigated and tested with examples. The reliability of the kinetic parameters as obtained by the iterative least‐squares lineshape fitting procedure is discussed.