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@INPROCEEDINGS{Daniel:1047025,
author = {Daniel, Davis Thomas and Bartsch, Christian Hippolyt and
Bereck, Franz Philipp and Scheurer, Christoph and Köcher,
Simone Swantje and Granwehr, Josef},
title = {{I}lt{P}y: {A} python library for inverse {L}aplace
transform of magnetic resonance data},
reportid = {FZJ-2025-04081},
year = {2025},
abstract = {Relaxation and diffusion processes offer rich information
about interactions anddynamics in materials and can be
correlated to chemical composition and structure.
[1]Experimental magnetic resonance data obtained from
relaxation and diffusionmeasurements are often analysed by
fitting a suitable mathematical function to the datafor
extracting underlying relaxation time and diffusion rate
constants. However,depending on the compositional
heterogeneity, processes may exhibit functionaldependencies
which are not governed by a single characteristic parameter
but adistribution. Therefore, experimentally measured data
may feature a superposition ofdifferent contributions, and
their disentanglement becomes challenging by
conventionaldata analysis methods. In such cases, inversion
algorithms allow for quantitativeanalysis by inverting the
data with a suitable kernel, mitigating the need for
possiblyambiguous assumptions regarding the number of
components or the shape of theunderlying distribution.
Herein, IltPy,[2] an open-source python library is
introduced forperforming regularized inverse Laplace
transforms (ILT) of one- and multi-dimensionaldata.
Conventional approaches to ILT of magnetic resonance data
require anassumption of signal contributions to be strictly
positive. [3] However, this approachsuppresses negative
contributions which may be physically relevant, particularly
insystems undergoing chemical exchange or
cross-relaxation.[4]IltPy implements regularized inverse
Laplace transform (ILT) without requiring non-negativity
(NN) constraints.[5] Tikhonov regularization in its
generalized form is used,and the solution is stabilized with
a uniform penalty and a zero-crossing penaltyallowing for
extraction of parameter distributions preserving both
positive and negativefeatures in the data without preferring
one of the signs. IltPy supports user-definedkernels and
validity of NN constraint can be tested by comparing
inversions with andwithout NN. For large data sets, singular
value decomposition is used to compressdata. For
experimental data with non-uniform noise or oscillatory
features, such asESEEM, IltPy supports weighted inversions.
Furthermore, resolution of multi-dimensional data may be
improved by regularization of non-inverted
dimensions.[2]IltPy is particularly suited for EPR and NMR
spectroscopic data. The performance ofthe library is
demonstrated using application examples from relaxation and
diffusiondata sets, revealing insights into interactions and
environments in complex systems.[1] Daniel, D.T. et. al.
Phys. Chem. Chem. Phys. 2023, 25, 12767–12776[2]
https://apps.fz-juelich.de/iltpy [Accessed 17.04.2025][3]
Provencher, S. Comput. Phys. Commun. 1982, 27, 213−227[4]
Rodts S, Bytchenkoff D. Journal of Magnetic Resonance. 2010,
205, 315-318.[5] Granwehr, J. et. al. Journal of chemical
theory and computation. 2012, 8,3473-3482},
month = {Sep},
date = {2025-09-15},
organization = {46. FGMR Annual Discussion Meeting
2025, Bonn (Germany), 15 Sep 2025 - 18
Sep 2025},
subtyp = {After Call},
cin = {IET-1},
cid = {I:(DE-Juel1)IET-1-20110218},
pnm = {1223 - Batteries in Application (POF4-122) / DFG project
G:(GEPRIS)441255373 - Design polymerbasierter organischer
Dünnschicht-Batterien hin zu IoT Anwendungen. (441255373)},
pid = {G:(DE-HGF)POF4-1223 / G:(GEPRIS)441255373},
typ = {PUB:(DE-HGF)6},
url = {https://juser.fz-juelich.de/record/1047025},
}