Mass spectrometry of hyper-velocity impacts of organic micrograins.

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.

[1]  E. Grün,et al.  The E-ring in the vicinity of Enceladus: II. Probing the moon's interior—The composition of E-ring particles , 2008 .

[2]  J. S. Kam,et al.  DUNE-eXpress Dust astronomy with ConeXpress , 2006 .

[3]  Ralf Srama,et al.  Low-charge detector for the monitoring of hyper-velocity micron-sized dust particles , 2008 .

[4]  M. Burchell,et al.  Synthesis and Characterization of Polypyrrole-Coated Sulfur-Rich Latex Particles: New Synthetic Mimics for Sulfur-Based Micrometeorites , 2006 .

[5]  M. Burchell,et al.  Acceleration of conducting polymer-coated latex particles as projectiles in hypervelocity impact experiments , 1999 .

[6]  Michael J. Cole,et al.  Time of flight mass spectra of ions in plasmas produced by hypervelocity impacts of organic and mineralogical microparticles on a cosmic dust analyser , 2003 .

[7]  M. Burchell,et al.  Sample return of interstellar matter (SARIM) , 2009 .

[8]  P. Ehrenfreund,et al.  ISO observations of interstellar ices: Implications for the pristinity of comets , 2000 .

[9]  Jan Hendrik Bredehöft,et al.  Identification of diamino acids in the Murchison meteorite. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[10]  W. Ip,et al.  Liquid water on Enceladus from observations of ammonia and 40Ar in the plume , 2009, Nature.

[11]  J. Kissel,et al.  Ion formation by high velocity impacts on porous metal targets , 2006 .

[12]  E. Igenbergs,et al.  The Cassini Cosmic Dust Analyzer , 2004 .

[13]  S. Armes,et al.  Synthesis and characterization of micrometersized polypyrrole‐coated polystyrene latexes* , 1995 .

[14]  M. Burchell,et al.  Impact ionization experiments with low density conducting polymer-based micro-projectiles as analogues of solar system dusts , 2002 .

[15]  C. Chyba,et al.  Cometary delivery of organic molecules to the early Earth. , 1990, Science.

[16]  Simon F. Green,et al.  Laboratory calibration of the Cassini Cosmic Dust Analyser (CDA) using new, low density projectiles , 2002 .

[17]  F. R. Krueger,et al.  Time-of-flight mass spectrometric analysis of ion formation in hypervelocity impact of organic polymer microspheres: comparison with secondary ion mass spectrometry, (252)Cf mass spectrometry and laser mass spectrometry. , 2001, Rapid communications in mass spectrometry : RCM.

[18]  James G. Bradley,et al.  Cosmic dust analyzer for Cassini , 1996, Optics & Photonics.

[19]  E. Grün,et al.  DEVELOPMENT OF AN ADVANCED DUST TELESCOPE , 2004 .

[20]  W. Huebner,et al.  First Polymer in Space Identified in Comet Halley , 1987, Science.

[21]  Tra-Mi Ho,et al.  Laboratory simulation improvements for hypervelocity micrometeorite impacts with a new dust particle source , 2001 .

[22]  E. Grün,et al.  Laboratory detection of organic dust with the Cassini-CDA instrument , 2004 .

[23]  F. R. Krueger,et al.  The organic component in dust from comet Halley as measured by the PUMA mass spectrometer on board Vega 1 , 1987, Nature.

[24]  E. Grün,et al.  The composition of Saturn's E ring , 2007 .

[25]  E. Grün,et al.  Large area mass analyzer instrument for the chemical analysis of interstellar dust particles. , 2007, The Review of scientific instruments.

[26]  E. Grün,et al.  2002 Kuiper prize lecture: Dust Astronomy , 2005 .