Interstellar and interplanetary carbonaceous solids in the laboratory

International audienceThe interstellar medium (ISM) is a physico-chemical laboratory where extreme conditions are encountered and whereparticular environmental parameters (e.g., density, reactant nature, radiation, temperature, time scales) define the compositionof matter. With present observational possibilities, the fundamental question regarding the possible link betweenISM and solar system samples can be addressed by astrophysicists, planetologists, and cosmochemists. This article focuseson observations of diffuse ISM and dust components of molecular clouds, setting constraints on the composition oforganic solids and large molecules associated with matter cycling in the Galaxy. This study aims at drawing somecommonalities and differences between the materials found in the Solar System and those found in interstellar dust

Interlaboratory assessment of nitrous oxide isotopomer analysis by isotope ratio mass spectrometry and laser spectroscopy: current status and perspectives

RATIONALEIn recent years, research and applications of the N2O site-specific nitrogen isotope composition have advanced, reflecting awareness of the contribution of N2O to the anthropogenic greenhouse effect, and leading to significant progress in instrument development. Further dissemination of N2O isotopomer analysis, however, is hampered by a lack of internationally agreed gaseous N2O reference materials and an uncertain compatibility of different laboratories and analytical techniques.METHODSIn a first comparison approach, eleven laboratories were each provided with N2O at tropospheric mole fractions (target gas T) and two reference gases (REF1 and REF2). The laboratories analysed all gases, applying their specific analytical routines. Compatibility of laboratories was assessed based on N2O isotopocule data for T, REF1 and REF2. Results for T were then standardised using REF1 and REF2 to evaluate the potential of N2O reference materials for improving compatibility between laboratories.RESULTSCompatibility between laboratories depended on the analytical technique: isotope ratio mass spectrometry (IRMS) results showed better compatibility for δ15N values, while the performance of laser spectroscopy was superior with respect to N2O site preference. This comparison, however, is restricted by the small number of participating laboratories applying laser spectroscopy. Offset and two-point calibration correction of the N2O isotopomer data significantly improved the consistency of position-dependent nitrogen isotope data while the effect on δ15N values was only minor.CONCLUSIONSThe study reveals that for future research on N2O isotopocules, standardisation against N2O reference material is essential to improve interlaboratory compatibility. For atmospheric monitoring activities, we suggest N2O in whole air as a unifying scale anchor. Copyright © 2014 John Wiley & Sons, Ltd