Corannulene and its complex with water: A tiny cup of water

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Far-IR and UV spectral signatures of controlled complexation and microhydration of the polycyclic aromatic hydrocarbon acenaphthene

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Accommodation in Europe low paid work and immigration issue

Conférence de clôture du projet Européen DYNAMO, Aix-en-Provence, 3-5 juillet, 50 p

Far-IR absorption of neutral polycyclic aromatic hydrocarbons (PAHs): light on the mechanism of IR–UV ion dip spectroscopy

Gas-phase IR–UV double-resonance laser spectroscopy is an IR absorption technique that bridges the gap between experimental IR spectroscopy and theory. The IR experiments are used to directly evaluate predicted frequencies and potential energy surfaces as well as to probe the structure of isolated molecules. However, a detailed understanding of the underlying mechanisms is, especially in the far-IR regime, still far from complete, even though this is crucial for properly interpreting the recorded IR absorption spectra. Here, events occurring upon excitation to vibrational levels of polycyclic aromatic hydrocarbons by far-IR radiation from the FELIX free electron laser are followed using resonance-enhanced multiphoton ionization spectroscopy. These studies provide detailed insight into how ladder climbing and anharmonicity influence IR–UV spectroscopy and therefore the resulting IR signatures in the far-IR region. Moreover, the potential energy surfaces of these low-frequency delocalized modes are investigated and shown to have a strong harmonic character.Laboratory astrophysics and astrochemistr

Rotational spectroscopy of imidazole: Accurate spectroscopic information for three vibrationally excited states and the heavy-atom isotopologues up to 295 GHz

International audienceWe report our analysis of the pure rotational spectra of low-lying vibrationally excited states and heavy-atom rare isotopologues of imidazole. To facilitate searches for imidazole in the interstellar medium, we previously described the analysis of the rotational spectrum of the imidazole main isotopologue across the 2–295 GHz range, and we extend this analysis here. Structure optimisation and anharmonic frequency calculations were performed to aid the spectral analysis. Three vibrationally excited states of imidazole were assigned in our room-temperature spectra, with energies up to approximately 670 cm−1 above the vibronic ground state. The vibrational states could act as temperature probes in warmer star-forming regions. The 13C and 15N heavy-atom isotopologues were assigned, which allowed for the structure of imidazole in the gas phase to be determined. Structural comparisons are drawn between the related heterocyclic molecules hydantoin and imidazolidine. An experimental gas-phase structure of the former is also determined in this work. The potential detection of the isotopologues could help deduce formation pathways towards imidazole and other nitrogen-containing cyclic compounds in interstellar space