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

**Visual EPR** gives you new advanced methods of experimental
spectra treatment without significant restrictions.

Let us consider, as an example, the very usual situation: during an investigation of some
crystal you obtained spectra which are not similar to observed ones before .

VIEW_SPW allows you in short time:

1. to review the dozen of experimental spectra and their parameters,

2. to estimate of effective g-factor value of any line,

3. to carry out filtering, base line correction and peak-picking,

4. to compare old and new spectra,

5. to subtract one spectrum from another and determine the difference between spectra,

6. to prepare a dependence of spectrum characteristics on variable parameter (frequency,
temperature, concentration, angular dependencies for
FAIW).

With the help of decomposition procedure of View_Spw.exe you can carry out more precize
analysis of complex spectrum:

1. separate overlaped lines,

2. estimate the main characteristics of spectrum - the position of resonance lines, their
shape, intensities and widths, the number of the components in multiplets and the values
of splitting between components,

3. determinate all line characteristics by fitting of experimental spectrum.

If you prepared a table with experimental values of resonance magnetic fields,
intensities and widths of lines for several orientations of constant magnetic field
(angular dependence) with the help of FAIW you
can:

1. see on screen (and, of course, obtain hard copy) your data with all conveniences
(choice of scales, zoom and so on),

2. estimate effective value of g-factor for any point on screen,

3. compare on one screen experimental angular dependence (graphic 1) with several
calculated dependencies (graphics 2, 3, ...) or compare several experimental dependencies,

4. subtract from the points of one graphic the points of all another ones, i.e. separate
new lines only in experimental angular dependencies,

5. carry out an identification of observed resonance lines and possible transitions by
comparing experimental data with the results of preliminary calculation with the help of ENERGY or FIELDS program,

6. prepare the table of data which are needed for determination of Spin-Hamiltonian
parameters with the help of PARAMS program.

PARAMS program permits:

1. to view experimental data,

2. to minimize difference between observed and calculated resonance magnetic fields for
chosen Spin-Hamiltonian,

3. to eliminate on screen accidental (error) points and restart calculation,

4. to change minimized function to avoid local minima,

5. to estimate accuracy of determination of Spin-Hamiltonian parameters, if accuracy of
experimental data is given.

And it is possible to make fitting of resonance fields, which was measured at different
microwave frequencies, for examples, in X and Q bands.

If it is necessary, you can transform obtained values of g or hyperfine interaction tensors into three main values and table of cosinuses or Euler angles for main axis directions (COSEUL).

After determination of Spin-Hamiltonian parameters you have the possibility with the
help of ENERGY program:

1. calculate dependence of energy levels on magnetic field and position of resonance
transitions and their intensities;

2. simulate a shape of spectra by substitution of resonance lines on Gaussian or
Lorentzian lines with user controlled width;

3. simulate for a comparison with experimental data the dependencies of spectrum shape

on line width,

on azimutal or polar angles,

on any parameter of Spin-Hamiltonian,

on microwave frequency

on temperature.

After calculation of angular dependencies of resonance lines and probabilities of the transitions with the help of FIELDS program you can compare them with experimental data (using FAIW) and, if all right, prepare for publication a picture with experimental data and theoretical curves - FAIW permits to join calculated positions of resonance transitions by continual lines and gives you a lot of special symbols to draw experimental points.

And the last but not a least: using **Visual EPR** you obtain a
possibility to economy the time, which you spent on perturbation theory calculations and
spectra treatment by hand, and to concentrate your attention on physical side of your
tasks.

We hope that **Visual EPR** will be useful and convenient for
solving the most of your problems.