Events & Seminars > Event Details

Where:

Room 304, Chemistry Building

Experimental Astrochemistry: From the Laboratory to the Stars – Dr. Holger Kreckel

Speaker:

Dr. Holger Kreckel
University of Illinois

Hosted by: Professor Kevin Lehmann

Dr. Kreckel’s Website

Please note that this is a Chemistry Faculty Hire seminar.

Abstract:
Approximately 160 molecules have been detected in space to date and new telescopes like Herschel and ALMA aim to unravel the molecular composition of the universe. Laboratory experiments can help us to understand the role of molecules in interstellar reaction networks today, as well as in the early universe.

In the dilute and cold interstellar medium, ion-neutral reactions are essential for the formation of larger molecules since they proceed rapidly even at low temperatures. The triatomic hydrogen ion H3 is a particularly important player in these environments where it serves as a universal proton-donor for almost any neutral reaction partner. The main destruction mechanism for H3+ in the diffuse interstellar medium is the Dissociative Recombination (DR) with free electrons. This process has been the subject of a long controversy that was settled by laboratory measurements only recently. I will present nuclear-spin-selective storage ring measurements of the H3+ DR process and spectroscopic studies of the H3+ ion and consider the results in the context of recent astronomical observations.
In contrast to today’s molecular clouds, the chemistry of the early universe is comparatively simple as only three elements (H, He, and Li) were produced in significant amounts by big bang nucleosynthesis. It has long been recognized that the formation of H2 is crucial for the creation of the first stars, as cooling through atomic transitions in hydrogen becomes inefficient at temperatures <10 000K. During the epoch of first star formation, H2 is formed via Associative Detachment (AD) of H and H. I will present the first energy-resolved laboratory measurement of the AD process and discuss its implications for the formation of the first stars.