@phdthesis{5d1bc1bc-39b3-40ac-93f3-18a4e15002cf,
  abstract     = {{This thesis investigates core excited electronic states of molecules in gas phase. In particular, the resonant<br/>transitions of ionised molecules, the site-selectivity surrounding Auger-Meitner decay, and the nuclear dynamics<br/>that may follow core excitation and ionisation.<br/><br/><b>Background:</b> Fundamental understanding of molecules and ions lay the groundwork for all future applicative<br/>science and production. For example, explicit understanding of dissociative mechanisms leads to control of chemical reactions.<br/><br/><b>Aims:</b> 1) To investigate molecular states after core photoexcitation in both molecules and ions. 2) To examine<br/>how the excited states decay through Auger-Meitner electron emission and how site-selectivity can be used to<br/>affect the decay rate. 3) To study the various nuclear geometrical changes (isomerisation, fragmentation or bond<br/>elongation) for the excited/ionised states.<br/><br/><b>Methods:</b> All the experiments done for this work utilised synchrotron radiation. The high resolution and<br/>frequency tunability are perfect for investigating resonant behaviours around the relevant energies (carbon K-edge). Three different experimental spectrometer types were used, an ion-trap with a reflectron mass spectrometer,<br/>hemispherical energy resolving electron analysers, and 3D momentum imaging spectrometers for charged particles.<br/><br/><b>Results:</b> X-ray absorption like spectra were obtained for new ions, CH<sup>+</sup><sub>3</sub> ,CH<sup>+</sup><sub>4</sub> , and CH<sup>+</sup><sub>5</sub> . The ionised versions<br/>of CH<sub>n</sub> revealed a much clearer picture of the various highly excited states which are not discernible in the neutral<br/>variant. The fluxional nature of CH<sup>+</sup><sub>5</sub> could be shown, as the spectrum was obtained from two geometrical<br/>structures.<br/><br/>The resonant Auger-Meitner decay spectra of ethyl trifluoroacetate (ESCA) and cyclohexadiene (CHD) revealed<br/>a clear state-selective process, and resonant behaviours.<br/><br/>The cyclic molecule cyclopropane showed different ring deforming dynamics dependent on which state was<br/>excited (σ<sup>*</sup> or π<sup>*</sup>). A specific dynamic in cyclopropane was also found, which was the roaming dissociation<br/>mechanism. The roaming was imaged with a 3D momentum spectrometer, and its existence was evident. This<br/>roaming motion leads to the formation of the H<sup>+</sup><sub>3</sub> ion.}},
  author       = {{Lindblom, Ville}},
  isbn         = {{978-91-8104-952-7}},
  keywords     = {{synchrotron radiation; multi-coincidence; fragmentation dynamics; molecular roaming; ion spectroscopy; x-ray absorption spectroscopy; photoelectron spectroscopy; Auger-Meitner decay; Auger electron spectroscopy}},
  language     = {{eng}},
  publisher    = {{Lunds universitet}},
  school       = {{Lund University}},
  title        = {{Spectroscopy of core-excited molecules and exploration of the induced dynamics}},
  url          = {{https://lup.lub.lu.se/search/files/248001477/Avhandling_Ville_Lindblom_LUCRIS.pdf}},
  year         = {{2026}},
}