Numerous descriptions of organic molecules present in the Murchison meteorite have improved our understanding of the early interstellar chemistry that operated at or just before the birth of our solar system. However, all molecular analyses were so far targeted toward selected classes of compounds with a particular emphasis on biologically active components in the context of prebiotic chemistry. Here we demonstrate that a nontargeted ultrahigh-resolution molecular analysis of the solvent-accessible organic fraction of Murchison extracted under mild conditions allows one to extend its indigenous chemical diversity to tens of thousands of different molecular compositions and likely millions of diverse structures. This molecular complexity, which provides hints on heteroatoms chronological assembly, suggests that the extraterrestrial chemodiversity is high compared to terrestrial relevant biologicaland biogeochemical-driven chemical space.Fourier transform ion cyclotron resonance mass spectrometry | interstellar chemistry | nuclear magnetic resonance spectroscopy | organic chondrite | soluble organic matter M urchison chondrite is one of the most studied meteorites and became a reference for extraterrestrial organic chemistry (1). The diversity of organic compounds recorded in Murchison and in other carbon-rich carbonaceous chondrites (1-5) has clearly improved our understanding of the early interstellar chemistry that operated at or just before the birth of our solar system. More than 70% of the Murchison carbon content has been classified as (macromolecular) insoluble organic matter (IOM) of high aromaticity, whereas the soluble fraction contains extensive suites of organic molecules with more than 500 structures identified so far (6). These structures basically resemble known biomolecules, but are considered to result from abiotic synthesis because of peculiar occurrence patterns, racemic mixtures, and stable isotope contents and distributions. Most of the 100+ kg fragments of Murchison were collected shortly after it fell in Australia on September 28, 1969, so that neither of these fresh samples suffered from intensive terrestrial weathering (7).As a whole, Murchison is one of the least-altered chondrites (8), recently reclassified by Rubin et al. (9) as CM2.5, where the aqueous alteration index (2.5 petrologic subtype), based on petrographic and mineralogical properties of the meteorite, indicates that the primary lithology of Murchison had experienced a relatively low and uniform degree of aqueous alteration.Nevertheless, all previous molecular analyses were targeted toward selected classes of compounds with a particular emphasis on amino acids in the context of prebiotic chemistry as potential source of life on earth (10), or on compounds obtained in chemical degradation studies (11) releasing both genuine extractable molecules and reaction products (11-15) often difficult to discern unambiguously.Alternative nontargeted investigations of complex organic systems are now feasible using advanced analytical met...

The gas phase reaction of ozone with beta-caryophyllene was investigated in a static glass reactor at 750 Torr and 296 K under various experimental conditions. The reactants and gas phase products were monitored by FTIR-spectroscopy and proton-transfer-reaction mass spectrometry (PTR-MS). Aerosol formation was monitored with a scanning mobility particle sizer (SMPS) and particulate products analysed by liquid chromatography/mass spectrometry (HPLC-MS). The different reactivity of the two double bonds in beta-caryophyllene was probed by experiments with different ratios of reactants. An average rate coefficient at 295 K for the first-generation products was determined as 1.1 x 10(-16) cm(3) molecule(-1) s(-1). Using cyclohexane as scavenger, an OH-radical yield of (10.4 +/- 2.3)% was determined for the ozonolysis of the more reactive internal double bond, whereas the average OH-radical yield for the ozonolysis of the first-generation products was found to be (16.4 +/- 3.6)%. Measured gas phase products are CO, CO(2) and HCHO with average yields of (2.0 +/- 1.8)%, (3.8 +/- 2.8)% and (7.7 +/- 4.0)%, respectively for the more reactive internal double bond and (5.5 +/- 4.8)%, (8.2 +/- 2.8)% and (60 +/- 6)%, respectively from ozonolysis of the less reactive double bond of the first-generation products. The residual FTIR spectra indicate the formation of an internal secondary ozonide of beta-caryophyllene. From experiments using HCOOH as a Criegee intermediate (CI) scavenger, it was concluded that at least 60% of the formed CI are collisionally stabilized. The aerosol yield in the ozonolysis of beta-caryophyllene was estimated from the measured particle size distributions. In the absence of a CI scavenger the yield ranged between 5 and 24%, depending on the aerosol mass. The yield increases with addition of water vapour or with higher concentrations of formic acid. In the presence of HCHO, lower aerosol yields were observed. This suggests that HCOOH adds to a Criegee intermediate to form a low-volatility compound responsible for aerosol formation. The underlying reaction mechanisms are discussed and compared with the results from the accompanying theoretical paper.

The O(3)-initiated oxidation of beta-caryophyllene, a sesquiterpene emitted in forested areas, was theoretically characterized for the first time using DFT quantum chemical calculations combined with statistical kinetic RRKM/master equation analysis and variational transition state theory. O(3)-Addition occurs primarily, >95%, on the endocyclic double bond without a barrier, leading to a total rate coefficient of 8.3 x 10(-24) T(3.05) exp(1028 K/T) cm(3) molecule(-1) s(-1), with a slight negative T-dependence. Thermal and chemically activated unimolecular reactions following this addition, including the so-called ester and hydroperoxide channels, and internal formation of the secondary ozonide, where characterized and quantified; a newly discovered reaction pathway through intersystem crossing from a dioxirane to a triplet bis(oxy) biradical intermediate is incorporated in the mechanism. The first generation product distribution at 298 K is predicted as 74% stabilized Criegee intermediates (CI), 8% OH radicals together with vinoxy-type 2-oxo alkyl radical co-products, 8% acids, 0.3% esters, and 9% CO(2) with two alkyl radical co-products. The thermalized CI can convert to the secondary ozonide in many reaction conditions, in particular the atmosphere; secondary ozonides are thus expected as dominant products of the beta-caryophyllene ozonolysis. These results are consistent with the experimental data presented in the accompanying paper (Part I). The temperature dependence and uncertainties of the product distribution are discussed. The high molecular weight oxygenated products, including beta-caryophyllonic acid and secondary ozonides, are expected to contribute to secondary organic aerosol formation.