Graduate Student
Department of Chemistry University of Virginia
Aspen Clements
ABOUT ME
I received my bachelors degree in chemistry at the University of Nebraska Kearney in 2015. Now I am a second year at the University of Virginia in Dr. Robin Garrod's group working on modeling astrophysical experiments using Monte Carlo modeling. Primarily, I have focused on the structure of H2O and how deposition parameters alters that structure. Some of the preliminary work I have done is below. In the future we plan on investigating how structure impacts trapping and movement of astrohpysically-important molecules such as CO and CO2.
LASTEST RESEARCH
Overview
Depiction of the star formation process where the color shows the prestellar stage and the final stage, the disk, is shown in blue. Panel a is an adaptation from Herbst & VanDishoeck (2009) describing proto-stellar evolution and its corresponding chemistry. The temperature increases from right to left along with the density and the evolution of CO shown in tandem. In panel b there is a TPD profile from laboratory experiments from Dr. Edith Fayolle's Thesis. The temperature is shown on the x-axis and CO desorption rate on the y-axis. At regions i and ii, CO is leaving the surface either from a CO-rich environment (i) or a water-rich environment (ii). Stages iii and iv correspond to CO leaving during the rearrangement of water (iii) and sublimates from the surface (iv). Panel c shows a preliminary model of a layered CO and H2O ice and how the structure changes with temperature. At 11 K the original layered ice is shown. The next temperature, 25 K, shows CO has diffused into the pore of the H2O ice. At 95 K the H2O has begun collapsing and the last temperature shows the water ice before desorption.
This video shows a model that is meant to replicate an experiment from Collings et al. 2004. A porous amorphous H2O ice is co-deposited with CO. CO is black and red and H2O is red and white. The ice is linearly heated. The CO begins to desorb around 25 K until 60 K. The CO that had not desorbed is trapped in the H2O. The H2O compacts and begins to desorb.