REFTIM, Version 7.4

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• Program Package

The program REFTIM calculates and fits the time spectra of the nuclear resonant reflectivity, delayed and prompt reflectivity curves and corresponding conversion electron Mössbauer spectrum (CEMS) for any multilayer structure, containing 57Fe, 151Eu, 149Sm, 119Sn or other isotopes if they have M1 Mössbauer transition. The experimental details of the nuclear resonance scattering technique with synchrotron radiation are described in the ID18 beamline Web pages.

REFTIM runs on Windows. The calculations are performed by FORTRAN 5.1 code. The program envelope is prepared by VISUAL C++. The theoretical background of the calculation method is described in the refs.[1-6]. It uses 4x4- propagation matrices simplified for grazing angles. The exact code is also available. The model file of the structure can be created automatically by a dialog regime or attached as a ready one. All parameters, which are possible to fit, are listed and any set of them can be chosen for variations. Different options and "merit functions" for the fit procedure are provided.

The program allows to compare theoretical spectra with experimental ones on graphs. The improvement of the suggested model of multilayer structure, including HFI parameters and depth distribution functions, is possible by a handle or automatic variations of the used parameters. The comparison of the result for different structure models is mostly effective "by eyes" on the graphs, the further refinement is possible sequentially by the one-parameter descending. You can follow the variations of the curves "on line". The corresponding energy spectra of the resonant absorption and reflectivity and the used model of the electronic density and HFI depth distribution (initial and following ones) are presented in dialog windows.

The main task of REFTIM is the extraction of the of hyperfine interaction parameters (HFI) and depth profiles for different HFI in the investigated multilayer from the delayed reflectivity curve and the set of the time spectra of the nuclear resonant reflectivity measured for different grazing angles. Examples of such kind of investigations are given in refs. [7-24].

The program was created by