The goal
Previous experiments have used a copper sample coated with polycrystalline gold as the grain mimic. However, gold is not a particularly relevant or realistic surface for simulating interstellar dust grains. IR spectroscopy has indicated that some of the dust is composed primarily of silicate materials and carbonaceous materials, thus we investigated the use of thin films of silicate nanoparticles derived from meteoritic materials.
The experimental procedure
The thin films were prepared for us by a group at Virginia Commonwealth University, Richmond from samples of the Murchison and Allende meteorites. The samples were initially ground by hand to give sub μm to 100 μm sized particles which were then used to create the nanoparticles. The nanoparticles were formed using laser vaporisation/controlled condensation (LVCC), the apparatus for which is shown on Figure ?. A pulsed Nd-Yag laser is used to vaporise the sample, producing particles ranging from atoms to the sub nm scale. Helium is used as a carrier gas to deposit the nanoparticles onto the gold sample. By using two plates held at different temperatures convection currents are set up which aid deposition.
The results
links and publications
