Binding energies, reactivity, and sputtering processes
It is now recognized that physical and chemical processes can occur on the surface of dust grains through adsorption/desorption processes, surface-catalyzed chemical reactions, and energetic surface processes involving cosmic-rays and ultraviolet radiation. These processes are very crucial in the dense and cold part of the ISM
(densities of 104 - 106 cm-3 and T = 10 K),
where dust particles can accrete icy mantles. These mantles are mainly composed of H2O and in small amounts by other species like CO, CH4, CO2, and NH3.
Key questions in this area of astrochemistry are
Experimental and theoretical data are fundamental to link observations and models, in particular binding energies, energy barriers, and reaction rates of all the major molecular and atomic species on astronomically relevant surfaces, represent the most relevant data.
A quantitative characterization of such processes is only possible through dedicated laboratory studies, i.e. under full control of a large set of parameters such as temperature,
atom-flux, and ice morphology.
Our main goals are:
The short-term goal is to build the trap, test it, characterize one 500 nm nanoparticle of SiO2 by measuring its mass, and then
move the entire setup in a cryogenic chamber. At the same time, with an ion sputtering or an electron gun, sputtering experiments can be performed.
Dust sputtering plays a crucial role in AGN-driven ouflows for instance, where destruction and formation of the dust can affect the thermal balance and the formation
of molecular gas.
On the long-term we aim to build a gas pipeline to deposit gas-phase molecules on the surface of the trapped particle and measure binding energies and reactivity.