Laboratory experiments are essential in exploring the mechanisms involved in stardust formation. One key question is how a metal is incorporated into dust for an environment rich in elements involved in stardust formation (C, H, O, Si). To address experimentally this question we have used a radiofrequency cold plasma reactor in which cyclic organosilicon dust formation is observed. Metallic (silver) atoms were injected in the plasma during the dust nucleation phase to study their incorporation in the dust. The experiments show formation of silver nanoparticles (~15 nm) under conditions in which organosilicon dust of size 200 nm or less is grown. The presence of AgSiO bonds, revealed by infrared spectroscopy, suggests the presence of junctions between the metallic nanoparticles and the organosilicon dust. Even after annealing we could not conclude on the formation of silver silicates, emphasizing that most of silver is included in the metallic nanoparticles. The molecular analysis performed by laser mass spectrometry exhibits a complex chemistry leading to a variety of molecules including large hydrocarbons and organometallic species. The reactivity of silver atoms/ions with acetylene was also studied in a laser vaporization source. Key organometallic species, AgnC2Hm (n=1-3; m=0-2), were identified and their structures and energetic data computed using density functional theory. This allows us to propose that molecular Ag-C seeds promote the formation of Ag clusters but also catalyze hydrocarbon growth. Throughout the article, we show how the developed methodology can be used to characterize the incorporation of metal atoms both in the molecular and dust phases. The reported methodology is a demonstration laying down the ground for future studies on metals of astrophysical interest such as iron.
Gravity anomaly from laboratory experiments to astrophysics
Instituto de Astrofisica de Canarias（加那利天体物理研究所）；INAF - Osservatorio Astronomico di Padova（意大利国家天体物理研究所帕多瓦天文台）；Università dell’Insubria（因苏布里亚大学）；INAF - Osservatorio Astronomico di Brera（意大利国家天体物理研究所布雷拉天文台）
Laboratory photo-chemistry of pyrene clusters: an efficient way to form large PAHs
在这项工作中，我们研究了小PAH团簇（例如，芘簇）。使用四极离子阱结合飞行时间（QIT-TOF）质谱进行实验。结果表明，在强辐射场的作用下，芘团簇转化为较大的多环芳烃。具体地，芘二聚体阳离子（例如，[C $_{16}$ H $_{10}$ $-$ C $_{16}$ H $_{9}$ ] $^+$或C $_{32}$ H $_{19}$ $^+$）将光致异构化和光致异构化为全芳族阳离子（PAH）（例如，C $_{32}$ H $_{16}$ $^+$）与激光照射。用量子化学计算方法研究了新生成的多环芳烃的结构和这些反应途径的离解能。这些研究提供了一种新的有效的演变路线，在星际介质（ISM）中形成的自下而上的过程，将抵消自上而下的转换成环和链的大的多环芳烃，并提供了一个水库的大的多环芳烃，可以转换成C $_{60}$和其他富勒烯和大的碳笼。
PRODIGE - envelope to disk with NOEMA: VII. (Complex) organic molecules in the NGC1333 IRAS4B1 outflow: A new laboratory for shock chemistry
Max-Planck-Institut für extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；University of Rochester（罗切斯特大学）；Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；Taiwan Astronomical Research Alliance (TARA)（台湾天文研究联盟）；Institute of Astronomy and Astrophysics, Academia Sinica（中央研究院天文及天文物理研究所）
Laboratory photo-chemistry of covalently bonded fluorene clusters: observation of an interesting PAH bowl-forming mechanism
富勒烯C $_{60}$是星际介质（ISM）中发现的最大的分子之一，已经提出通过大的（超过60个C原子）多环芳烃（PAH）分子的光化学处理自上而下形成。在这篇文章中，我们专注于相反的过程，调查富勒烯形成的可能性，从小的多环芳烃，其中碗形成起着核心作用。我们结合实验室实验和量子化学计算来研究带电芴团簇形成较大的多环芳烃。实验表明，在可见激光照射下，芴二聚体阳离子- [C $_{13}$ H $_{9}$ $-$ C $_{13}$ H $_{9}$ ] $^+$ -和芴三聚体阳离子- [C $_{13}$ H $_{8}$ $-$ C $_{13}$ H $_{9}$ ] $^+$ -发生光脱氢和光异构化，产生碗状结构的芳香簇离子，C $_{26}$ H $_{12}$ $^+$和C $_{39}$ H $_{20}$ $^+$。为了研究这个化学过程的细节，我们采用量子化学，使我们能够确定新形成的簇离子的结构，计算氢损失解离能，并推导出潜在的反应途径。这些结果表明，较小的多环芳烃簇（小于60个碳原子）可以转化为较大的碗状几何结构，可能作为富勒烯的构建块，因为碗形成机制大大促进了从脱氢多环芳烃到笼的转化。此外，碗状的形成诱导了一个永久的偶极矩，原则上允许使用射电天文学来寻找这样的物种。
SPARCS -- combining radiation hydrodynamics with non-equilibrium metal chemistry in the SWIFT astrophysical code
the Chinese University of Hong Kong（香港中文大学）；the University of Chicago（芝加哥大学）；University of Hull（赫尔大学）；Durham University（杜伦大学）；Leiden University（莱顿大学）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；Université de Genève（日内瓦大学）
