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String Fit : a new structurally oriented X‐ray and neutron reflectivity evaluation technique
Author(s) -
Politsch Erich
Publication year - 2001
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889801001832
Subject(s) - x ray reflectivity , radius of gyration , neutron , neutron scattering , inversion (geology) , computational physics , radius , scattering , reflectivity , optics , physics , statistical physics , molecular physics , computer science , nuclear magnetic resonance , quantum mechanics , polymer , paleontology , computer security , structural basin , biology
A novel method for the analysis of neutron and X‐ray reflectivity measurements is presented. In contrast to existing methods, the new data fitting approach is structurally oriented and therefore only requires information about the chemical structure of studied molecules and no other ad hoc assumptions. Apart from the inversion of reflectivity into scattering length density profile, the inversion of scattering length density profile into molecular arrangement is addressed systematically for non‐trivial molecular conformations for the first time. This includes the calculation of structural characteristics, such as radius of gyration or chain order parameters, based on measured reflectograms. Another important option is the possibility to evaluate simultaneously neutron and X‐ray reflectograms of a given sample. For better convergence, especially for complex simultaneous evaluations, an effective extension of the normally used least‐squares deviation function is introduced. Different simulated molecular ensembles are used to illustrate the features of the new approach; typically, excellent agreement between the simulated starting and final deduced data sets is achieved.