Dr Antonin Knizek

Abstract:

Time-resolved Fourier transform infrared emission spectroscopy, Fourier transform absorption infrared spectroscopy, and high-resolution UV–ViS emission spectroscopy have been used to characterize the chemistry of isocyanic acid (HNCO) under glow discharge conditions in planetary atmospheres. HNCO mixtures (i.e., composed of di-hydrogen or ammonia) have been investigated in order to unveil the possible reaction pathways leading to the synthesis of the key prebiotic molecule formamide (HCONH2), upon planetary atmospheres containing isocyanic acid in presence of di-hydrogen and, separately, of ammonia. In addition, ab initio molecular dynamics simulations coupled with a modern metadynamics technique have been performed in order to identify the most likely chemical pathways connecting HNCO to formamide. It turned out that the direct hydrogenation of HNCO is thermodynamically favored. Incidentally, the experimental results – supplied by a simplified kinetic model – also proved the favorability of the reaction HNCO + H2→ HCONH2which, moreover, spontaneously takes place in unbiased ab initio molecular dynamics simulations carried out under the effect of intense electric fields.

Abstract:

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Abstract:

Aims. We aim to analyse real-time Perseid and Leonid meteor spectra using a novel calibration-free (CF) method, which is usually applied in the laboratory for laser-induced breakdown spectroscopic (LIBS) chemical analysis. Methods. Reference laser ablation spectra of specimens of chondritic meteorites were measured in situ simultaneously with a high-resolution laboratory echelle spectrograph and a spectral camera for meteor observation. Laboratory data were subsequently evaluated via the CF method and compared with real meteor emission spectra. Additionally, spectral features related to airglow plasma were compared with the spectra of laser-induced breakdown and electric discharge in the air. Results. We show that this method can be applied in the evaluation of meteor spectral data observed in real time. Specifically, CF analysis can be used to determine the chemical composition of meteor plasma, which, in the case of the Perseid and Leonid meteors analysed in this study, corresponds to that of the C-group of chondrites.