Investigation of multiple electronic excited state relaxation pathways following 200 nm photolysis of gas-phase imidazole
Yu, Hui, Evans, Nicholas L., Stavros, Vasilios G. and Ullrich, Susanne. (2012) Investigation of multiple electronic excited state relaxation pathways following 200 nm photolysis of gas-phase imidazole. Physical Chemistry Chemical Physics, Vol.14 (No.18). pp. 6266-6272. ISSN 1463-9076Full text not available from this repository.
Official URL: http://dx.doi.org/10.1039/C2CP23533A
midazole acts as a subunit in the DNA base adenine and the amino acid histidine—both important biomolecules which display low fluorescence quantum yields following UV excitation. The low fluorescence quantum yields are attributed to competing non-radiative excited state relaxation pathways that operate on ultrafast timescales. Imidazole is investigated here as a model compound due to its accessibility to high level ab initio calculations and time-resolved gas-phase spectroscopic techniques. Recent non-adiabatic dynamics simulations have identified three non-radiative relaxation mechanisms which are active following 6.0–6.2 eV excitation. Presented herein is a comprehensive investigation of each mechanism using a combination of femtosecond time-resolved ion yield and total kinetic energy release spectroscopies to monitor the formation of associated photoproducts. Relaxation along the 1πσ*NH state constitutes the predominant deactivation pathway. Timescales for NH-dissociation are extracted and distinguished from alternative H-atom sources based on their kinetic energy distributions. Larger photoproducts are observed to a lesser extent and attributed to ring fragmentation following NH-puckering and CN-stretching relaxation paths.
|Item Type:||Journal Article|
|Divisions:||Faculty of Science > Chemistry|
|Journal or Publication Title:||Physical Chemistry Chemical Physics|
|Publisher:||Royal Society of Chemistry|
|Page Range:||pp. 6266-6272|
|Access rights to Published version:||Restricted or Subscription Access|
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