title: Mass spectrometry of hyper-velocity impacts of organic micrograins.
abstract: The study of hyper-velocity impacts of micrometeoroids is important for the calibration of dust sensors in space applications. For this purpose, submicron-sized synthetic dust grains comprising either polystyrene or poly[bis(4-vinylthiophenyl)sulfide] were coated with an ultrathin overlayer of an electrically conductive organic polymer (either polypyrrole or polyaniline) and were accelerated to speeds between 3 and 35 km s(-1) using the Heidelberg Dust Accelerator facility. Time-of-flight mass spectrometry was applied to analyse the resulting ionic impact plasma using a newly developed Large Area Mass Analyser (LAMA). Depending on the projectile type and the impact speed, both aliphatic and aromatic molecular ions and cluster species were identified in the mass spectra with masses up to 400 u. Clusters resulting from the target material (silver) and mixed clusters of target and projectile species were also observed. Impact velocities of between 10 and 35 km s(-1) are suitable for a principal identification of organic materials in micrometeoroids, whereas impact speeds below approximately 10 km s(-1) allow for an even more detailed analysis. Molecular ions and fragments reflect components of the parent molecule, providing determination of even complex organic molecules embedded in a dust grain. In contrast to previous measurements with the Cosmic Dust Analyser instrument, the employed LAMA instrument has a seven times higher mass resolution--approximately 200--which allowed for a detailed analysis of the complex mass spectra. These fundamental studies are expected to enhance our understanding of cometary, interplanetary and interstellar dust grains, which travel at similar hyper-velocities and are known to contain both aliphatic and aromatic organic compounds.
authors.affiliation: Max Planck Institute Nuclear Physics, Saupfercheckweg 1, 69117 Heidelberg, Germany. ralf.srama@mpi-hd.mpg.de
authors.forename: Ralf
authors.initials: R
authors.lastname: Srama
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Woiwode
authors.forename: Frank
authors.initials: F
authors.lastname: Postberg
authors.forename: Steven P
authors.initials: SP
authors.lastname: Armes
authors.forename: Syuji
authors.initials: S
authors.lastname: Fujii
authors.forename: Damien
authors.initials: D
authors.lastname: Dupin
authors.forename: Jonathan
authors.initials: J
authors.lastname: Ormond-Prout
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Sternovsky
authors.forename: Sascha
authors.initials: S
authors.lastname: Kempf
authors.forename: Georg
authors.initials: G
authors.lastname: Moragas-Klostermeyer
authors.forename: Anna
authors.initials: A
authors.lastname: Mocker
authors.forename: Eberhard
authors.initials: E
authors.lastname: Grün
mesh_terms: D019443:Cosmic Dust / Q000032:analysis*; D013058:Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry; D010316:Particle Size
chemical_list: D019443:Cosmic Dust; D009930:Organic Chemicals