WMOSS4R
(available as licensed version)
Above is given as example a series of 6 spectra taken from 3K to 300K. There are 3 inequivalent high spin Fe(3+) positions, each having almost similar Hint and IS parameters but only two positions have similar QS splittings. Strong spectra overlap is observed, both at low temperature conditions with strong applied fields as well as at high temperatures. Each of the three types of Fe position have however different relaxation parameters therefore with help from WMOSS4R the time independent hyperfine parameters are possible to be deconvoluted. In addition to this result, a large portion from the spin dynamics problem is solved too. The use of an time-dependent spin hamiltonian (in this case S=5/2, axial symmetry) confirms this method as a viable tool in resolving with exceptional precision the value of the uniaxial parameter D for ZFS tensor.

For spectra above, beside the hyperfine and relaxation parameters, our time dependent Mössbauer spectra analysis indicates a phase transition at 77K (in this example the dEq beta Euler angle varies with temperature from 0° to 90°, e.g. a change from longitudinal to transversal relaxation) leading to a change of relaxation parameters. Such conclusion would have been hidden in a standard time-independent approach and would obviously create major problems for a quantitative Mössbauer analysis using only those terms.
The above examples are excerpts from an initial test fit. Later refinements of parameters have led to better fits.
The time dependent spin-hamiltonian implemented in WMOSS4R is based on the well known Blume stochastic theory with applications to longitudinal or transversal hyperfine relaxation in axial Kramers systems with S up to 5/2. The algorithm and method used to implement this teory for spin-spin or spin-lattice mechanisms combine the practical developments of Afanasev, Bhargava and Mörup. Since the implementation of time dependent problem was made to be fully compatible with the previously available time independent hamiltonians, WMOSS4R will naturally allow to use a mixed models approach in your simultaneous-fits (combinations of slow-intermediate-fast relaxations at local or global levels).
Additional capability for 8-spectra simultaneous fits (each max. 14 subspectra wide with various model) offered in WMOSS4R means that quantitative analysis of larger and more complex problems are now feasible.
WMOSS.ORG helps adopting WMOSS4R analysis tool by offering a free (online) demonstration.