Contribution Invited Talk
Non-energetic processes at the surface of dust grains
The synthesis of molecules is a long and convoluted process. The molecular universe begins at the border of molecular clouds, and chemical complexity increases throughout the star formation process (Caselli & Ceccarelli 2012). Interstellar dust grains play many roles in the evolution of clouds, stars and planets, and among them, grains are effective catalytic centers, sometimes called chemical nanofactories. Unfortunately the direct observation of the chemical solid phase is a challenge for astronomy, and therefore a very good knowledge of the processes between gas and grains is required to handle gas phase observables.
For a decade we have developed laboratory astrophysics experiments centered around the synthesis of molecules from atoms and radicals on cold amorphous surfaces, mimicking interstellar conditions (Dulieu et al 2005). In my presentation I will explain how in the lab we can study some of the chemical networks, thanks to the example of the formation of water (Chaabouni et al 2012). I will briefly present new advances in chemistry, and focus on potentially meaningful mechanisms. I will explain how newly formed in the gas phase after their formation on the surface, and try to estimate the efficiency of this chemical desorption (Dulieu et al 2013, Minissale et al 2015a). I will finish by presenting new results about binding energies of O, and N atoms (Minissale et al 2015b), and some new aspects of the segregation of the species at the surface of grains that can affect their desorption energies (Noble et al 2012, 2015).
- Paola Caselli and Cecilia Ceccarelli. 2012. « Our Astrochemical Heritage ». The Astronomy and Astrophysics Review 20 : 1‑68. doi:10.1007/s00159-012-0056-x.
- Francois Dulieu, Emanuele Congiu, Jennifer Noble, Saoud Baouche, Henda Chaabouni, Audrey Moudens, Marco Minissale, et Stéphanie Cazaux. 2013. « How micron-sized dust particles determine the chemistry of our Universe ». Nature Scientific Reports 3 : 1338. doi:10.1038/srep01338.
- Marco Minissale, Francois Dulieu, Seyit Hocuk, Stephanie Cazaux, “Last gas before the frost: part I Quantifying chemical desorption and its impact on interstellar gas”, submitted to A&A
- Marco Minissale, Emanuele Congiu and Francois Dulieu, “Direct measurement of desorption and diffusion energies of O and N atoms physisorbed on amorphous surfaces” submitted to A&A
- Noble, J. A., Congiu, E., Dulieu, F., & Fraser, H. J. (2012). “Thermal desorption characteristics of CO, O2 and CO2 on non-porous water, crystalline water and silicate surfaces at submonolayer and multilayer coverages “. Monthly Notices of the Royal Astronomical Society, 421(1), 768–779. doi:10.1111/j.1365-2966.2011.20351.x
- Jenny Noble, Stephan Diana and Francois Dulieu, “Segregation of O2 and CO on the surface of dust grains determines the desorption energy of O2”, accepted in MNRAS