TY - GEN A1 - Lever, Fabiano A1 - Mayer, Dennis A1 - Metje, Jan A1 - Alisauskas, Skirmantas A1 - Calegari, Francesca A1 - Düsterer, Stefan A1 - Feifel, Raimund A1 - Niebuhr, Mario A1 - Manschwetus, Bastian A1 - Kuhlmann, Marion A1 - Mazza, Tommaso A1 - Robinson, Matthew Scott A1 - Squibb, Richard J. A1 - Trabattoni, Andrea A1 - Wallner, Måns A1 - Wolf, Thomas J. A. A1 - Gühr, Markus T1 - Core-level spectroscopy of 2-thiouracil at the sulfur L1 and L2,3 edges utilizing a SASE free-electron-laser T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - In this paper, we report X-ray absorption and core-level electron spectra of the nucleobase derivative 2-thiouracil at the sulfur L1- and L2,3-edges. We used soft X-rays from the free-electron laser FLASH2 for the excitation of isolated molecules and dispersed the outgoing electrons with a magnetic bottle spectrometer. We identified photoelectrons from the 2p core orbital, accompanied by an electron correlation satellite, as well as resonant and non-resonant Coster–Kronig and Auger–Meitner emission at the L1- and L2,3-edges, respectively. We used the electron yield to construct X-ray absorption spectra at the two edges. The experimental data obtained are put in the context of the literature currently available on sulfur core-level and 2-thiouracil spectroscopy. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1180 KW - X-ray KW - photoelectron KW - sulfur KW - thiouracil KW - nucleobases KW - Coster–Kronig KW - Auger–Meitner KW - NEXAFS KW - FLASH Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-524091 SN - 1866-8372 IS - 21 ER - TY - JOUR A1 - Lever, Fabiano A1 - Mayer, Dennis A1 - Metje, Jan A1 - Alisauskas, Skirmantas A1 - Calegari, Francesca A1 - Düsterer, Stefan A1 - Feifel, Raimund A1 - Niebuhr, Mario A1 - Manschwetus, Bastian A1 - Kuhlmann, Marion A1 - Mazza, Tommaso A1 - Robinson, Matthew Scott A1 - Squibb, Richard J. A1 - Trabattoni, Andrea A1 - Wallner, Måns A1 - Wolf, Thomas J. A. A1 - Gühr, Markus T1 - Core-level spectroscopy of 2-thiouracil at the sulfur L1 and L2,3 edges utilizing a SASE free-electron-laser JF - Molecules N2 - In this paper, we report X-ray absorption and core-level electron spectra of the nucleobase derivative 2-thiouracil at the sulfur L1- and L2,3-edges. We used soft X-rays from the free-electron laser FLASH2 for the excitation of isolated molecules and dispersed the outgoing electrons with a magnetic bottle spectrometer. We identified photoelectrons from the 2p core orbital, accompanied by an electron correlation satellite, as well as resonant and non-resonant Coster–Kronig and Auger–Meitner emission at the L1- and L2,3-edges, respectively. We used the electron yield to construct X-ray absorption spectra at the two edges. The experimental data obtained are put in the context of the literature currently available on sulfur core-level and 2-thiouracil spectroscopy. KW - X-ray KW - photoelectron KW - sulfur KW - thiouracil KW - nucleobases KW - Coster–Kronig KW - Auger–Meitner KW - NEXAFS KW - FLASH Y1 - 2021 SN - 1420-3049 VL - 26 IS - 21 PB - MDPI CY - Basel ER - TY - THES A1 - Mayer, Dennis T1 - Time-resolved x-ray spectroscopy of 2-thiouracil T1 - Zeitaufgelöste Röntgenspektroskopie an 2-Thiouracil N2 - In this thesis, I present my contributions to the field of ultrafast molecular spectroscopy. Using the molecule 2-thiouracil as an example, I use ultrashort x-ray pulses from free- electron lasers to study the relaxation dynamics of gas-phase molecular samples. Taking advantage of the x-ray typical element- and site-selectivity, I investigate the charge flow and geometrical changes in the excited states of 2-thiouracil. In order to understand the photoinduced dynamics of molecules, knowledge about the ground-state structure and the relaxation after photoexcitation is crucial. Therefore, a part of this thesis covers the electronic ground-state spectroscopy of mainly 2-thiouracil to provide the basis for the time-resolved experiments. Many of the previously published studies that focused on the gas-phase time-resolved dynamics of thionated uracils after UV excitation relied on information from solution phase spectroscopy to determine the excitation energies. This is not an optimal strategy as solvents alter the absorption spec- trum and, hence, there is no guarantee that liquid-phase spectra resemble the gas-phase spectra. Therefore, I measured the UV-absorption spectra of all three thionated uracils to provide a gas-phase reference and, in combination with calculations, we determined the excited states involved in the transitions. In contrast to the UV absorption, the literature on the x-ray spectroscopy of thionated uracil is sparse. Thus, we measured static photoelectron, Auger-Meitner and x-ray absorption spectra on the sulfur L edge before or parallel to the time-resolved experiments we performed at FLASH (DESY, Hamburg). In addition, (so far unpublished) measurements were performed at the synchrotron SOLEIL (France) which have been included in this thesis and show the spin-orbit splitting of the S 2p photoline and its satellite which was not observed at the free-electron laser. The relaxation of 2-thiouracil has been studied extensively in recent years with ultrafast visible and ultraviolet methods showing the ultrafast nature of the molecular process after photoexcitation. Ultrafast spectroscopy probing the core-level electrons provides a complementary approach to common optical ultrafast techniques. The method inherits its local sensitivity from the strongly localised core electrons. The core energies and core-valence transitions are strongly affected by local valence charge and geometry changes, and past studies have utilised this sensitivity to investigate the molecular process reflected by the ultrafast dynamics. We have built an apparatus that provides the requirements to perform time-resolved x-ray spectroscopy on molecules in the gas phase. With the apparatus, we performed UV-pump x-ray-probe electron spectroscopy on the S 2p edge of 2-thiouracil using the free-electron laser FLASH2. While the UV triggers the relaxation dynamics, the x-ray probes the single sulfur atom inside the molecule. I implemented photoline self-referencing for the photoelectron spectral analysis. This minimises the spectral jitter of the FEL, which is due to the underlying self-amplified spontaneous emission (SASE) process. With this approach, we were not only able to study dynamical changes in the binding energy of the electrons but also to detect an oscillatory behaviour in the shift of the observed photoline, which we associate with non-adiabatic dynamics involving several electronic states. Moreover, we were able to link the UV-induced shift in binding energy to the local charge flow at the sulfur which is directly connected to the electronic state. Furthermore, the analysis of the Auger-Meitner electrons shows that energy shifts observed at early stages of the photoinduced relaxation are related to the geometry change in the molecule. More specifically, the observed increase in kinetic energy of the Auger-Meitner electrons correlates with a previously predicted C=S bond stretch. N2 - In dieser Arbeit präsentiere ich meine Beiträge zum Gebiet der ultraschnellen Molekülspektroskopie. Am Beispiel des Moleküls 2-Thiouracil verwende ich ultrakurze Röntgenpulse von Freie-Elektronen-Lasern, um die Relaxationsdynamik von Molekülproben in der Gasphase zu untersuchen. Unter Ausnutzung der für Röntgenstrahlung typischen Element- und Ortsselektivität untersuche ich den Ladungsfluss und die geometrischen Veränderungen in den angeregten Zuständen von 2-Thiouracil. Um die photoinduzierte Dynamik von Molekülen zu verstehen, ist das Wissen über die Grundzustandsstruktur und die Relaxation nach Photoanregung entscheidend. Daher befasst sich ein Teil dieser Arbeit mit der elektronischen Grundzustandsspektroskopie von 2-Thiouracil, um die Grundlage für die zeitaufgelösten Experimente zu schaffen. Viele der bisher veröffentlichten Studien, die sich mit der zeitaufgelösten Dynamik von Thiouracilen in der Gasphase nach UV-Anregung befassten, stützten sich zur Bestimmung der Anregungsenergien auf Informationen aus der Spektroskopie in Lösung. Dies ist nicht optimal, da Lösungsmittel das Absorptionsspektrum verändern und es daher keine Garantie dafür gibt, dass die Spektren in Lösung den Spektren der Gasphase ähneln. Daher habe ich die UV-Absorptionsspektren aller drei Thiouracile gemessen, um eine Referenz für die Gasphase zu erhalten, und in Kombination mit Berechnungen die an den Übergängen beteiligten angeregten Zustände bestimmt. Im Gegensatz zur UV-Absorption ist die Literatur zur Röntgenspektroskopie von thioniertem Uracil spärlich. Daher haben wir statische Photoelektronen-, Auger-Meitner- und Röntgenabsorptionsspektren an der Schwefel-L-Kante vor oder parallel zu den zeitaufgelösten Experimenten an FLASH (DESY, Hamburg) gemessen. Darüber hinaus wurden (bisher unveröffentlichte) Messungen am Synchrotron SOLEIL (Frankreich) durchgeführt, die in diese Arbeit eingeflossen sind und die Spin-Orbit-Aufspaltung der S 2p-Photolinie und ihres Satelliten zeigen, die am Freie-Elektronen-Laser nicht beobachtet wurde. Die Relaxation von 2-Thiouracil wurde in den letzten Jahren ausgiebig mit ultraschnellen Methoden im sichtbaren und ultravioletten Spektralbereich untersucht, die die ultraschnelle Natur des molekularen Prozesses nach der Photoanregung zeigen. Die ultraschnelle Spektroskopie, bei der die Elektronen des Kernniveaus untersucht werden, bietet einen ergänzenden Ansatz zu den üblichen optischen Techniken. Die Methode erhält ihre lokale Empfindlichkeit durch die stark lokalisierten Kernelektronen. Die Kernenergien und Kern-Valenz-Übergänge werden stark von lokalen Valenzladungs- und Geometrieänderungen beeinflusst, und frühere Studien haben diese Empfindlichkeit genutzt, um den molekularen Prozess zu untersuchen, der sich in der ultraschnellen Dynamik widerspiegelt. Wir haben eine Apparatur gebaut, die die Voraussetzungen für die Durchführung zeitaufgelöster Röntgenspektroskopie an Molekülen in der Gasphase bietet. Mit dieser Apparatur haben wir Anregungs-Abfrage-Elektronenspektroskopie an der S 2p-Kante von 2-Thiouracil an dem Freie-Elektronen-Laser FLASH2 durchgeführt. Zuerst triggert ein UV-Puls die Relaxationsdynamik und anschließend tastet ein Röntgenpuls das einzelne Schwefelatom im Inneren des Moleküls ab. Für die Analyse der Photoelektronenspektren habe ich eine Selbstrefernzierung der Photolinie implementiert, mit deren Hilfe der spektrale Jitter des FEL minimiert werden konnte. Dieser ist auf den zugrunde liegenden Prozess der selbstverstärkten spontanen Emission (SASE) zurückzuführen. Mit diesem Ansatz konnten wir nicht nur dynamische Veränderungen in der Bindungsenergie der Elektronen untersuchen, sondern auch ein oszillierendes Verhalten in der Verschiebung der beobachteten Photolinie feststellen, das wir mit einer nicht-adiabatischen Dynamik in Verbindung bringen, an der mehrere elektronische Zustände beteiligt sind. Außerdem konnten wir die UV-induzierte Verschiebung der Bindungsenergie mit dem lokalen Ladungsfluss am Schwefel in Verbindung bringen, der direkt mit dem elektronischen Zustand verbunden ist. Darüber hinaus zeigt die Analyse der Auger-Meitner-Elektronen, dass die in frühen Stadien der photoinduzierten Relaxation beobachteten Energieverschiebungen mit der Geometrieänderung des Moleküls zusammenhängen. Genauer gesagt korreliert der beobachtete Anstieg der kinetischen Energie der Auger-Meitner-Elektronen mit einer zuvor vorhergesagten Dehnung der C=S-Bindung. KW - thiouracil KW - ultrafast molecular dynamics KW - x-ray spectroscopy KW - Auger-Meitner electron spectroscopy KW - photoelectron spectroscopy KW - free-electron laser KW - FLASH KW - excited-state chemical shift KW - Thiouracil KW - ultraschnelle Moleküldynamik KW - Röntgenspektroskopie KW - Photoelektronenspektroskopie KW - pump-probe spectroscopy KW - Freie-Elektronen-Laser KW - Anregungs-Abfrage-Spektroskopie Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-571636 ER - TY - JOUR A1 - Mayer, Dennis A1 - Lever, Fabiano A1 - Gühr, Markus T1 - Data analysis procedures for time-resolved x-ray photoelectron spectroscopy at a SASE free-electron-laser JF - Journal of physics : B, Atomic, molecular and optical physics N2 - The random nature of self-amplified spontaneous emission (SASE) is a well-known challenge for x-ray core level spectroscopy at SASE free-electron lasers (FELs). Especially in time-resolved experiments that require a combination of good temporal and spectral resolution the jitter and drifts in the spectral characteristics, relative arrival time as well as power fluctuations can smear out spectral-temporal features. We present a combination of methods for the analysis of time-resolved photoelectron spectra based on power and time corrections as well as self-referencing of a strong photoelectron line. Based on sulfur 2p photoelectron spectra of 2-thiouracil taken at the SASE FEL FLASH2, we show that it is possible to correct for some of the photon energy drift and jitter even when reliable shot-to-shot photon energy data is not available. The quality of pump-probe difference spectra improves as random jumps in energy between delay points reduce significantly. The data analysis allows to identify coherent oscillations of 1 eV shift on the mean photoelectron line of 4 eV width with an error of less than 0.1 eV. KW - free-electron laser KW - photoelectron spectroscopy KW - FLASH Y1 - 2022 U6 - https://doi.org/10.1088/1361-6455/ac3c91 SN - 0953-4075 SN - 1361-6455 VL - 55 IS - 5 PB - IOP Publ. CY - Bristol ER - TY - GEN A1 - Mayer, Dennis A1 - Lever, Fabiano A1 - Picconi, David A1 - Metje, Jan A1 - Ališauskas, Skirmantas A1 - Calegari, Francesca A1 - Düsterer, Stefan A1 - Ehlert, Christopher A1 - Feifel, Raimund A1 - Niebuhr, Mario A1 - Manschwetus, Bastian A1 - Kuhlmann, Marion A1 - Mazza, Tommaso A1 - Robinson, Matthew Scott A1 - Squibb, Richard James A1 - Trabattoni, Andrea A1 - Wallner, Måns A1 - Saalfrank, Peter A1 - Wolf, Thomas J. A. A1 - Gühr, Markus T1 - Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220–250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1301 Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-577442 SN - 1866-8372 N1 - These authors contributed equally: D. Mayer, F. Lever. A Publisher Correction to this article was published on 09 March 2022. This article has been updated. IS - 1301 ER - TY - JOUR A1 - Mayer, Dennis A1 - Lever, Fabiano A1 - Picconi, David A1 - Metje, Jan A1 - Ališauskas, Skirmantas A1 - Calegari, Francesca A1 - Düsterer, Stefan A1 - Ehlert, Christopher A1 - Feifel, Raimund A1 - Niebuhr, Mario A1 - Manschwetus, Bastian A1 - Kuhlmann, Marion A1 - Mazza, Tommaso A1 - Robinson, Matthew Scott A1 - Squibb, Richard James A1 - Trabattoni, Andrea A1 - Wallner, Måns A1 - Saalfrank, Peter A1 - Wolf, Thomas J. A. A1 - Gühr, Markus T1 - Following excited-state chemical shifts in molecular ultrafast x-ray photoelectron spectroscopy JF - Nature Communications N2 - The conversion of photon energy into other energetic forms in molecules is accompanied by charge moving on ultrafast timescales. We directly observe the charge motion at a specific site in an electronically excited molecule using time-resolved x-ray photoelectron spectroscopy (TR-XPS). We extend the concept of static chemical shift from conventional XPS by the excited-state chemical shift (ESCS), which is connected to the charge in the framework of a potential model. This allows us to invert TR-XPS spectra to the dynamic charge at a specific atom. We demonstrate the power of TR-XPS by using sulphur 2p-core-electron-emission probing to study the UV-excited dynamics of 2-thiouracil. The method allows us to discover that a major part of the population relaxes to the molecular ground state within 220–250 fs. In addition, a 250-fs oscillation, visible in the kinetic energy of the TR-XPS, reveals a coherent exchange of population among electronic states. Y1 - 2022 U6 - https://doi.org/10.1038/s41467-021-27908-y SN - 2041-1723 N1 - These authors contributed equally: D. Mayer, F. Lever. A Publisher Correction to this article was published on 09 March 2022. This article has been updated. VL - 13 PB - Springer Nature CY - Berlin ER - TY - JOUR A1 - Mayer, Dennis A1 - Matthaei, Christian T. A1 - Heuer, Axel A1 - Gühr, Markus T1 - Kagome-fiber prism compressor combination for Yb BT - KGW laser pulse compression to sub-40fs JF - Journal of optics N2 - Spectral broadening in hollow-core fibers is an important tool for pulse compression of low-peak power laser pulses, especially for Yb-based lasers. Here, we present a pulse compression scheme to reduce the pulse duration of a commercial Yb:KGW laser operating at 100 kHz repetition rate and 40 mu J pulse energy from 390 to 38 fs. The spectral broadening is accomplished using a krypton-filled Kagome-type fiber. We report broadened spectra for variable Kr-pressures and input powers. At optimal settings of 8 bar Kr-pressure and 3.3 W input power, the bandwidth of the pulse at the -10 dB level increased from 9.5 to 85 nm corresponding to a Fourier limit of 26 fs. A simple SF10 prism compressor is used to reduce the accumulated chirp and shortens the fiber output from about 500 to 38 fs. In addition to the spectral broadening, a pressure dependent change of the polarization is observed. KW - pulse compression KW - ultrafast optics KW - photonic crystal fibers Y1 - 2019 U6 - https://doi.org/10.1088/2040-8986/aafdf6 SN - 2040-8978 SN - 2040-8986 VL - 21 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Mayer, Dennis A1 - Picconi, David A1 - Robinson, Matthew S. A1 - Gühr, Markus T1 - Experimental and theoretical gas-phase absorption spectra of thionated uracils JF - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature N2 - We present a comparative study of the gas-phase UV spectra of uracil and its thionated counterparts (2-thiouracil, 4-thiouracil and 2,4-dithiouracil), closely supported by time-dependent density functional theory calculations to assign the transitions observed. We systematically discuss pure gas-phase spectra for the (thio)uracils in the range of 200-400 nm (similar to 3.2-6.4 eV), and examine the spectra of all four species with a single theoretical approach. We note that specific vibrational modelling is needed to accurately determine the spectra across the examined wavelength range, and systematically model the transitions that appear at wavelengths shorter than 250 nm. Additionally, we find in the cases of 2-thiouracil and 2,4-dithiouracil, that the gas-phase spectra deviate significantly from some previously published solution-phase spectra, especially those collected in basic environments. KW - Thiouracil KW - Uracil KW - UV-VIS Spectroscopy KW - Excited-state calculations; KW - TD-DFT KW - Gas phase Y1 - 2022 U6 - https://doi.org/10.1016/j.chemphys.2022.111500 SN - 0301-0104 VL - 558 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Metje, Jan A1 - Lever, Fabiano A1 - Mayer, Dennis A1 - Squibb, Richard James A1 - Robinson, Matthew Scott A1 - Niebuhr, Mario A1 - Feifel, Raimund A1 - Düsterer, Stefan A1 - Gühr, Markus T1 - URSA-PQ BT - A Mobile and Flexible Pump-Probe Instrument for Gas Phase Samples at the FLASH Free Electron Laser JF - Applied Sciences N2 - We present a highly flexible and portable instrument to perform pump-probe spectroscopy with an optical and an X-ray pulse in the gas phase. The so-called URSA-PQ (German for ‘Ultraschnelle Röntgenspektroskopie zur Abfrage der Photoenergiekonversion an Quantensystemen’, Engl. ‘ultrafast X-ray spectroscopy for probing photoenergy conversion in quantum systems’) instrument is equipped with a magnetic bottle electron spectrometer (MBES) and tools to characterize the spatial and temporal overlap of optical and X-ray laser pulses. Its adherence to the CAMP instrument dimensions allows for a wide range of sample sources as well as other spectrometers to be included in the setup. We present the main design and technical features of the instrument. The MBES performance was evaluated using Kr M4,5NN Auger lines using backfilled Kr gas, with an energy resolution ΔE/E ≅ 1/40 in the integrating operative mode. The time resolution of the setup at FLASH 2 FL 24 has been characterized with the help of an experiment on 2-thiouracil that is inserted via the instruments’ capillary oven. We find a time resolution of 190 fs using the molecular 2p photoline shift and attribute this to different origins in the UV-pump—the X-ray probe setup. KW - X-ray probe KW - molecular dynamics KW - gas phase electron spectroscopy Y1 - 2020 U6 - https://doi.org/10.3390/app10217882 SN - 2076-3417 VL - 10 IS - 21 PB - MDPI CY - Basel ER - TY - GEN A1 - Metje, Jan A1 - Lever, Fabiano A1 - Mayer, Dennis A1 - Squibb, Richard James A1 - Robinson, Matthew Scott A1 - Niebuhr, Mario A1 - Feifel, Raimund A1 - Düsterer, Stefan A1 - Gühr, Markus T1 - URSA-PQ BT - A Mobile and Flexible Pump-Probe Instrument for Gas Phase Samples at the FLASH Free Electron Laser T2 - Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe N2 - We present a highly flexible and portable instrument to perform pump-probe spectroscopy with an optical and an X-ray pulse in the gas phase. The so-called URSA-PQ (German for ‘Ultraschnelle Röntgenspektroskopie zur Abfrage der Photoenergiekonversion an Quantensystemen’, Engl. ‘ultrafast X-ray spectroscopy for probing photoenergy conversion in quantum systems’) instrument is equipped with a magnetic bottle electron spectrometer (MBES) and tools to characterize the spatial and temporal overlap of optical and X-ray laser pulses. Its adherence to the CAMP instrument dimensions allows for a wide range of sample sources as well as other spectrometers to be included in the setup. We present the main design and technical features of the instrument. The MBES performance was evaluated using Kr M4,5NN Auger lines using backfilled Kr gas, with an energy resolution ΔE/E ≅ 1/40 in the integrating operative mode. The time resolution of the setup at FLASH 2 FL 24 has been characterized with the help of an experiment on 2-thiouracil that is inserted via the instruments’ capillary oven. We find a time resolution of 190 fs using the molecular 2p photoline shift and attribute this to different origins in the UV-pump—the X-ray probe setup. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1016 KW - X-ray probe KW - molecular dynamics KW - gas phase electron spectroscopy Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-483073 SN - 1866-8372 IS - 1016 ER - TY - JOUR A1 - Robinson, Matthew Scott A1 - Niebuhr, Mario A1 - Lever, Fabiano A1 - Mayer, Dennis A1 - Metje, Jan A1 - Gühr, Markus T1 - Ultrafast photo-ion probing of the ring-opening process in trans-stilbene oxide JF - Chemistry - a European journal N2 - The ultrafast photo-induced ring opening of the oxirane derivative trans-stilbene oxide has been studied through the use of ultrafast UV/UV pump-probe spectroscopy by using photo-ion detection. Single- and multiphoton probe paths and final states were identified through comparisons between UV power studies and synchrotron-based vacuum ultraviolet (VUV) single-photon ionization studies. Three major time-dependent features of the parent ion (sub-450 fs decay, (1.5 +/- 0.2) ps, and >100 ps) were observed. These decays are discussed in conjunction with the primary ring-opening mechanism of stilbene oxide, which occurs through C-C dissociation in the oxirane ring. The appearance of fragments relating to the masses of dehydrogenated diphenylmethane (167 amu) and dehydrogenated methylbenzene (90 amu) were also investigated. The appearance of the 167 amu fragment could suggest an alternative ultrafast ring-opening pathway via the dissociation of one of the C-O bonds within the oxirane ring. KW - femtochemistry KW - mass spectrometry KW - photochemistry KW - small ring systems KW - stilbene oxide Y1 - 2021 U6 - https://doi.org/10.1002/chem.202101343 SN - 1521-3765 VL - 27 IS - 44 SP - 11418 EP - 11427 PB - Wiley-VCH CY - Weinheim ER -