Real-time tracking of energy flow in cluster formation

Abstract Femtosecond time-resolved spectroscopy has shaped our understanding of light-matter interaction at the atomic level. However, the photoinduced formation of chemical bonds, especially for larger aggregates, has evaded observation due to difficulties to prepare reactants at well-defined initi...

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Main Authors: Michael Stadlhofer, Bernhard Thaler, Pascal Heim, Josef Tiggesbäumker, Markus Koch
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:Communications Chemistry
Online Access:https://doi.org/10.1038/s42004-025-01563-6
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author Michael Stadlhofer
Bernhard Thaler
Pascal Heim
Josef Tiggesbäumker
Markus Koch
author_facet Michael Stadlhofer
Bernhard Thaler
Pascal Heim
Josef Tiggesbäumker
Markus Koch
author_sort Michael Stadlhofer
collection DOAJ
description Abstract Femtosecond time-resolved spectroscopy has shaped our understanding of light-matter interaction at the atomic level. However, the photoinduced formation of chemical bonds, especially for larger aggregates, has evaded observation due to difficulties to prepare reactants at well-defined initial conditions. Here, we overcome this hurdle by taking advantage of the exceptional solvation properties of superfluid helium, which allow us to stabilize atoms in a metastable, foam-like configuration with 10 Å interatomic distance. We apply photoexcitation with a femtosecond laser pulse to collapse such a dilute metastable aggregate of Mg atoms formed inside a nanometer-sized He droplet, and track cluster formation at a characteristic time of (450 ± 180) fs through photoionization with a time-delayed second pulse. We find that energy pooling collisions of electronically excited Mg atoms occur during cluster formation, leading to transient population of highly-excited Mg atoms, up to 3 eV above the excitation photon energy. Relaxation and conversion to nuclear kinetic energy drives cluster fragmentation and ejection of ionic fragments from the droplet. Our results demonstrate the potential of He droplets for bond formation studies, and for revealing involved energy- and charge transfer dynamics, like photon energy upconversion.
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spelling doaj-art-dba95553edfa423689b16ecb69e365b22025-08-20T02:39:02ZengNature PortfolioCommunications Chemistry2399-36692025-05-01811910.1038/s42004-025-01563-6Real-time tracking of energy flow in cluster formationMichael Stadlhofer0Bernhard Thaler1Pascal Heim2Josef Tiggesbäumker3Markus Koch4Institute of Experimental Physic, Graz University of TechnologyInstitute of Experimental Physic, Graz University of TechnologyInstitute of Experimental Physic, Graz University of TechnologyInstitute of Physics, University of RostockInstitute of Experimental Physic, Graz University of TechnologyAbstract Femtosecond time-resolved spectroscopy has shaped our understanding of light-matter interaction at the atomic level. However, the photoinduced formation of chemical bonds, especially for larger aggregates, has evaded observation due to difficulties to prepare reactants at well-defined initial conditions. Here, we overcome this hurdle by taking advantage of the exceptional solvation properties of superfluid helium, which allow us to stabilize atoms in a metastable, foam-like configuration with 10 Å interatomic distance. We apply photoexcitation with a femtosecond laser pulse to collapse such a dilute metastable aggregate of Mg atoms formed inside a nanometer-sized He droplet, and track cluster formation at a characteristic time of (450 ± 180) fs through photoionization with a time-delayed second pulse. We find that energy pooling collisions of electronically excited Mg atoms occur during cluster formation, leading to transient population of highly-excited Mg atoms, up to 3 eV above the excitation photon energy. Relaxation and conversion to nuclear kinetic energy drives cluster fragmentation and ejection of ionic fragments from the droplet. Our results demonstrate the potential of He droplets for bond formation studies, and for revealing involved energy- and charge transfer dynamics, like photon energy upconversion.https://doi.org/10.1038/s42004-025-01563-6
spellingShingle Michael Stadlhofer
Bernhard Thaler
Pascal Heim
Josef Tiggesbäumker
Markus Koch
Real-time tracking of energy flow in cluster formation
Communications Chemistry
title Real-time tracking of energy flow in cluster formation
title_full Real-time tracking of energy flow in cluster formation
title_fullStr Real-time tracking of energy flow in cluster formation
title_full_unstemmed Real-time tracking of energy flow in cluster formation
title_short Real-time tracking of energy flow in cluster formation
title_sort real time tracking of energy flow in cluster formation
url https://doi.org/10.1038/s42004-025-01563-6
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AT pascalheim realtimetrackingofenergyflowinclusterformation
AT joseftiggesbaumker realtimetrackingofenergyflowinclusterformation
AT markuskoch realtimetrackingofenergyflowinclusterformation