Structural Sensitivity of N 1s Excitations in <i>N</i>-Methylacetamide Solutions - UTU Research Portal

A1 Refereed original research article in a scientific journal

Structural Sensitivity of N 1s Excitations in N-Methylacetamide Solutions

Authors: Eronen, E. A.; Vladyka, A.; Sahle, Ch. J.; Niskanen, J.

Publisher: American Chemical Society (ACS)

Publication year: 2025

Journal: Journal of Physical Chemistry Letters

Journal name in source: The Journal of Physical Chemistry Letters

Volume: 16

Issue: 7

First page : 1666

Last page: 1672

ISSN: 1948-7185

eISSN: 1948-7185

DOI: https://doi.org/10.1021/acs.jpclett.4c03487

Web address : https://doi.org/10.1021/acs.jpclett.4c03487

Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/484802289

Abstract

Interpreting the X-ray spectra of liquids is complicated by their selective structural sensitivity and ensemble averaging. We report nitrogen K-edge spectra of liquid N-methylacetamide and its water solutions at temperatures of 305 and 350 K. The pre-peak in the spectrum shows a shift with an increase in the temperature or N-methylacetamide concentration. The effect is reproduced by our classical molecular dynamics simulations and subsequent spectrum calculations using density functional theory. We apply a data-driven method, emulator-based component analysis, to the computational data to identify the decisive structural degrees of freedom behind spectral variation. This representation in reduced dimensions accounts for the involved loss of structural information and reveals that the effect is indicative of weakening of the hydrogen bonds.

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Funding information in the publication:
E.A.E. acknowledges the Jenny and Antti Wihuri foundationand the Magnus Ehrnrooth foundation for funding. Theauthors acknowledge the Academy of Finland for funding viaProject 331234, the Finnish IT Center for Science (CSC) andthe Finnish Grid and Cloud Infrastructure (FGCI) forcomputing resources, and the European Synchrotron RadiationFacility (ESRF) for provision of synchrotron radiation facilitiesunder Proposal IH-SC-1792 at beamline ID20.