In our group we push the boundaries of how we can study molecules in the gas-phase. We develop novel methods to transfer ever large and more fragile (neutral) systems into the gas-phase, as well as new ways to control and probe these molecules. This development of these new methodologies is driven by scientific curiosity, but also real-world applications such as new analytical techniques.

Current Research in the group:

You can also find some recent posters from the group in the gallery!

Structural-isomer effects in photochemistry

We know that in nature small structural changes – the rotation around a single bond or the relocation of a hydrogen atom – can significantly alter chemical functionality. But actually studying the structure-function relationship on this level is very challenging, as it is often impossible to separate these distinguish these different molecular structures. Yet this is exactly what we aim to do in this project by combining the electrostatic deflection technique with time-resolved spectroscopic methods. The electrostatic deflector allow us to select a single structural isomer (such as a conformer or tautomer) on the basis of its dipole moment. The isomer-selected samples can then be probes used methods that are not inherently isomer-sensitive themselves, such as ultrafast time-resolved photoelectron imaging experiments. This combination allows us to investigate how small structural changes, such as isomerism, influence the underlying photochemistry and chemical functionality.

Recent publications:

Abma, Grite L.; Parkes, Michael A.; Horke, Daniel A.: Preparation of Tautomer-Pure Molecular Beams by Electrostatic Deflection. In: J. Phys. Chem. Lett., vol. 15, no. 17, pp. 4587-4592, 2024. (Type: Journal Article | Links | BibTeX | Altmetric)
Abma, Grite L.; Kleuskens, Dries; Wang, Siwen; Balster, Michiel; Roij, Andre; Janssen, Niek; Horke, Daniel A.: Single-Color Isomer-Resolved Spectroscopy. In: The Journal of Physical Chemistry A, vol. 126, pp. 3811–3815, 2022. (Type: Journal Article | Abstract | Links | BibTeX | Altmetric)
Teschmit, Nicole; Horke, Daniel A.; Küpper, Jochen: Spatially Separating the Conformers of a Dipeptide. In: Angew. Chem. Int. Ed., vol. 57, pp. 13775–13779, 2018. (Type: Journal Article | Links | BibTeX | Altmetric)

Detecting chiral molecules with photoelectron circular dichroism

Chiral molecules, that is molecules with non-superimposable mirror images, are of crucial importance in pharmaceutical, agricultural and chemical industries. Yet the reliable and fast quantisation of chirality, and measurement of the enantiomeric excess, are non trivial. One promising new approach to detect chirality is imaging the photoelectrons produced following ionisation of a molecule by circular-polarised light (photoelectron circular dichroism – PECD). This approach has been shown to have orders of magnitude higher chiral responses than established analytical approaches.

As part of a consortium of partners from both academia and industry we are working on developing photoelectron circular dichroism (PECD) spectroscopy as an analytical tool. In particular we work closely together with the start-up MassSpecpecD on the development of a compact PECD-spectrometer for analytical applications.

Novel analytical tools for biomolecules

We are developing novel tools to analyse and study biologically relevant molecules (and other fragile systems) in the gas-phase. In particular we are developing soft vaporisation methods, that allows the intact transfer of large, fragile or non-volatile species into the gas-phase. Here we can study them using state-of-the-art spectroscopic or mass spectrometry techniques.

In particular we are working on a new approach termed laser-based thermal desorption (LBTD) that allows us to transfer fragile molecules from dilute solutions into the gas-phase, via deposition onto a thin inert metal foil. We have recently shown that this even allows us to transfer dipeptides or lipids intact in the spectrometer chamber, and at high densities.

Recent Publications

Wang, Siwen; Dauletyarov, Yerbolat; Horke, Daniel A.: High-Throughput UV Photoionization and Fragmentation of Neutral Biomolecules as a Structural Fingerprint. In: Molecules, vol. 28, no. 13, pp. 5058, 2023, ISSN: 1420-3049. (Type: Journal Article | Abstract | Links | BibTeX | Altmetric)
Dauletyarov, Yerbolat; Wang, Siwen; Horke, Daniel A.: Vaporization of Intact Neutral Biomolecules Using Laser-Based Thermal Desorption. In: J. Am. Soc. Mass Spectrom., vol. 34, pp. 1538, 2023, ISSN: 1044-0305, 1879-1123. (Type: Journal Article | Abstract | Links | BibTeX | Altmetric)
Wang, Siwen; Dauletyarov, Yerbolat; Krüger, Peter; Horke, Daniel A.: High-throughput UV-photofragmentation studies of thymine and guanine. In: Phys. Chem. Chem. Phys., vol. 25, pp. 12322, 2023. (Type: Journal Article | Abstract | Links | BibTeX | Altmetric)
Huang, Zhipeng; Ossenbrüggen, Tim; Rubinsky, Igor; Schust, Matthias; Horke, Daniel A; Küpper, Jochen: Development and Characterization of a Laser-Induced Acoustic Desorption Source. In: Anal. Chem., vol. 90, no. 6, pp. 3920–3927, 2018. (Type: Journal Article | Links | BibTeX | Altmetric)

New probes for time-resolved photochemistry

Recent advances in optical technologies now offer unprecedented opportunities for producing coherent and short-pulsed light (lasers) also at high photon energies, such as in the XUV (extreme ultraviolet) and even x-ray spectral regions. These allow us to explore new ways of performing time-resolved spectroscopies. In particular in combination with methods based on photoionization, such as photoelectron spectroscopy, this enables the realization of so-called universal probes, that can follow a photochemical process from reactants, through intermediates, to final products in real-time.

In collaboration with the group of Russell Minns (Southampton, UK) and the Artemis facility (STFC, Rutherford-Appleton lab) we are working on using XUV radiation produced through high-harmonic generation as a probe for photochemical processes.

Recent publications:

Abma, Grite L.; Parkes, Michael A.; Razmus, Weronika O.; Zhang, Yu; Wyatt, Adam S.; Springate, Emma; Chapman, Richard T.; Horke, Daniel A.; Minns, Russell S.: Direct Observation of a Roaming Intermediate and Its Dynamics. In: J. Am. Chem. Soc., vol. 146, no. 18, pp. 12595-12600, 2024. (Type: Journal Article | Links | BibTeX | Altmetric)
Warne, Emily M.; Smith, Adam D.; Horke, Daniel A.; Springate, Emma; Jones, Alfred J. H.; Cacho, Cephise; Chapman, Richard T.; Minns, Russell S.: Time Resolved Detection of the S(1D) Product of the UV Induced Dissociation of CS2. In: J. Chem. Phys., vol. 154, no. 3, pp. 034302, 2021, ISSN: 0021-9606, 1089-7690. (Type: Journal Article | Abstract | Links | BibTeX | Altmetric)
Smith, Adam D.; Warne, Emily M.; Bellshaw, Darren; Horke, Daniel A.; Tudorovskya, Maria; Springate, Emma; Jones, Alfred J. H.; Cacho, Cephise; Chapman, Richard T.; Kirrander, Adam; Minns, Russell S.: Mapping the Complete Reaction Path of a Complex Photochemical Reaction. In: Phys. Rev. Lett., vol. 120, no. 18, pp. 183003, 2018. (Type: Journal Article | Abstract | Links | BibTeX | Altmetric)

Dynamics of electron-driven processes

Studying the dynamics of photon-driven processes (i.e. photochemistry!) is now a well established method. However, there is more to chemistry than photon-driven processes and reactions. In this new project we aim to ‘transfer’ many of the techniques we have developed to study photon-driven processes towards studying electron-driven processes (i.e. electrochemistry!). We aim to establish time-resolved electron-pump photon-probe spectroscopy to directly follow chemical processes initiated by electrons. In particular, we are interested in (dissociative) electron attachment reactions. These are at the heart of many biological damage processes, both detrimental (ionising radiation that destroys DNA) and beneficial (radiation therapy as a cancer treatment).


New paper in JPCA

Our latest paper using coincidence double-VMI imaging to distinguish neutral and ionic multiphoton dissociation channels in molecular oxygen is out now in JPCA – well done Ana!
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Yerbolat joins as PostDoc

Yerbolat joins the group as a PostDoc to work on your NWO-funded project on electron-driven reactions – Welcome Yerbolat!
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New paper in EPJD

Our latest paper comparing continuous and pulsed laser-based desorption (LIAD) methods is out now in Eur.Phys.J. D – well done Siwen!
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New paper in JPCA

Our latest paper showing how the electrostatic deflector can be used as a tool for isomer-resolved spectroscopy is out now in JPCA – well done Grite!
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Beamtime at LCLS

Grite is off to California for measurements using LCLS at SLAC, California. Good Luck!
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