Everyday programs for students and researchers in
physics, chemistry and biology, who uses

Electron Paramagnetic resonance (**EPR**),
Electron Spin Resonance (**ESR**),
and Electron Magnetic Resonance (**EMR**)

Programs, their destination and possiblities

Spin-Hamiltonian

Interrelations of
programs of the Visual EPR package

**See also**

How to use Visual EPR programs for the treatment of crystal spectra

Frequently Asked Questions

VIEW_SPW - shows experimental spectra (binary or ASCII formats) and carry out preliminary treatment of them: zoom, comparing, filtering, smoothing, Fourier transformation, peak-peaking, estimation of effective g-factor value, width and intensity of any line.

FIELDS - calculates resonance magnetic fields and intensities of EPR lines and their angular dependencies for the rotation of magnetic field in arbitrary plane or road map. Special search algorithm is used to obtain resonance magnetic fields with desirable accuracy in reasonable time. The programs permit simultaneously to carry out the calculations for all equivalent centers: their magnetic coordinate axes are related to the initial coordinate system by sets of Euler angles, as well as reflections in mirror planes.

ENERGY -
this part of the **Fields.exe** calculates dependencies of energy
levels on magnetic field, as well as dependencies of spectrum shape on azimutal
and polar angles, line width, microwave frequency and any parameter of Spin-Hamiltonian.

PARAMS - obtains parameters of Spin-Hamiltonian by fitting of calculated and experimental angular dependencies of EPR spectra.

FAIW- visualisates experimental or
calculated angular dependencies of resonance magnetic fields and convert into
special symbols the information about line intensity and width. It permits also to extract
the points, what you need, from array of experimental data and to prepare the data for
fitting with the help of **Params.exe**.

COSEUL - calculates main values of symmetric second rank tensors, the cosinuses of main axes and Euler angles of main coordinate system with respect to initial one.

HELP - there is a general tutorial "Visual EPR. Basics", as well as separate tutorials for every program.

One part of the spin-Hamiltonian is treated using exact numerical diagonalization of
its matrices.The number of particles (electrons and nuclei) in this part can be up to
9; total rank of Spin-Hamiltonian matrix
have to be less than 128. Point group symmetry, the number of parameters in the
Spin-Hamiltonian and values of these parameters are not restricted. The second
part of the spin-Hamiltonian includes comparatively small hyperfine and
quadrupole interactions of electrons with nuclei (up to 99 nuclei).This part is
treated as perturbation.

**View_spw.exe** is
the basic program, which you can use immediately after measurements for the
spectrum treatment. It prepares spectra and files with
four-dimensional tables for other programs.

**View_spw.exe** can
be used for preparation of spectral files for
**Fields.exe** (filtering, baseline correction, and algebraic
procedures).

**View_spw.exe**
must be used to prepare angular dependencies of experimental spectra for
comparison with calculated dependencies with the help of
**Fields.exe** and for refinement of obtained spin-Hamiltonian
parameters by fitting with **Params.exe**.

**FAIW.exe** can be
used for editing experimental angular dependencies obtained with the help of
**View_spc.exe**.

**Fields.exe** must
be used to prepare calculated angular dependencies for comparison with
experimental ones.

**Params.exe** can
be used for refinement of obtained spin-Hamiltonian parameters by fitting
experimental angular dependencies. It uses angular dependencies edited with the
help of **FAIW.exe**.

- V.G.Grachev.
*Correct expression for generalized spin-Hamiltonian of non-cubic paramagnetic center.*-*Sov. Phys.-**JETP*, 1987, v. 92, No 5, 1834-1844. - V.G. Grachev.
*G-symmetry and theory of ENDOR frequencies for centers with low-symmetry interactions*.- In:*Radiospectroscopy of Solid State*, Kiev: Naukova Dumka, 1993, p. 16-66 (in Russian).

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Revised: June 05, 2013.