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Brant Jones - University of Hawaii

Thursday, May 28 – 2:00-2:45PM

 

“Reaction Dynamics within the Interstellar Medium”

 

Ever since the pioneering detection of CH, CH+, and CN in interstellar space more than half a century ago, the formation of molecules in extraterrestrial environments has fascinated scientists. We now know of about 140 species, ranging in complexity from diatomics such as molecular hydrogen (H2) to polyatomics like benzene (C6H6) and the sugar glycolaldehyde (HOCH2CHO), which have been identified as gas-phase constituents of extraterrestrial environments. As the telescopes used to collect information about interstellar medium evolve and become ever more sensitive, multiple complex molecular species are expected to be discovered in this century.  Nevertheless, many facets of the questi­on "How do these molecules arise in the interstellar medium?" remain highly speculative. 

This talk presents an overview how molecules can be formed in extraterrestrial environments both in the gas phase and in interstellar ices. First, an overview of the crossed molecular beams apparatus will be presented; we will show how this instrument can be used to help elucidate the formation of the molecular species observed within the gas phase of the interstellar medium. Specifically preliminary results on the formation of benzene and of the phenyl radical will be discussed – two crucial building blocks suggested to be involved in the formation of polycyclic aromatic hydrocarbons (PAHs) and related compounds. These PAHs are thought to be linked to the formation of carbonaceous, interstellar grains; in cold molecular clouds, these grains can hold temperatures as low as 10 K thus acting as natural cold traps for molecular species to be condensed upon. The second part of the talk expands on these grains and presents how astrobiologically important molecules can be formed in these ices as condensed on interstellar grains via ionizing radiation. Finally, we present an overview of our newly designed surface scattering machine simulating the space environment of the carbonaceous grains and the molecules deposited upon them and the effects that the galactic radiation has on these compounds.  The coupling of these instruments will allow an unprecedented understanding of how complex molecular species such as sugars, amino acids, and even polypeptides can be produced within the interstellar medium.

 

Related Reference(s):

X. Gu and R. I. Kaiser, “Reaction Dynamics of Phenyl Radicals in Extreme Environments: A Crossed Molecular Beam Study,” Acc. Chem. Res., 42, 290-302 (2009).

L. Zhou, R. I. Kaiser, L. G. Gao, A. H. H. Chang, M-C. Liang, Y. L. Yung, “Pathways to Oxygen-Bearing Molecules in the Interstellar Medium and in Planetary Atmospheres: Cyclopropenone (c-C3H2O) and Propynal (HCCCHO),” ApJ, 686, 1493-1502 (2008).