Thermal desorption of astrophysically relevant molecules from forsterite(010)

Abstract

We present temperature programmed desorption (TPD) measurements of CO, CH 4 , O 2 and CO 2 from the forsterite(010) surface in the sub-monolayer and multilayer coverage regimes. In the case of CO, CH 4 and O 2 , multilayer growth begins prior to saturation of the monolayer peak, resulting in two clearly distinguishable desorption peaks. On the other hand a single peak for CO 2 is observed which shifts from high temperature at low coverage to low temperature at high coverages, sharpening upon multilayer formation. The leading edges are aligned for all the molecules in the multilayer coverage regime indicating zero order desorption. We have extracted multilayer desorption energies for these molecules using an Arrhenius analysis. For sub-monolayer coverages, we observe an extended desorption tail to higher temperature. Inversion analysis has been used to extract the coverage dependent desorption energies in the sub-monolayer coverage regime, from which we obtain the desorption energy distribution. We found that owing to the presence of multiple adsorption energy sites on the crystalline surface the typical desorption energies of these small molecules are significantly larger than obtained in previous measurements for several other substrates. Therefore molecules bound to crystalline silicate surfaces may remain locked in the solid state for a longer period of time before desorption into the gas phase.

Surface Science Investigations of Icy Mantle Growth on Interstellar Dust Grains in Cooling Environments

“…Kay and co-workers were the first to report a simple inversion analysis which advanced the interpretation of submonolayer desorption data on grains . Work by Dulieu, Lemaire, Kay, McCoustra, Vidali, and Zacharias illustrates this procedure. ,− Table summarizes this state-of-the-art in TPD.…”

“…31 Work by Dulieu, Lemaire, Kay, McCoustra, Vidali, and Zacharias illustrates this procedure. 23,[32][33][34][35][36] Table 1 summarises this state-of-the-art in TPD.…”

Photodesorption of Water Ice from Dust Grains and Thermal Desorption of Cometary Ices Studied by the INSIDE Experiment

“…There is a huge number of laboratory studies of temperature-programmed desorption (TPD) of interstellar ice analogues (for reviews see (Burke & Brown 2010;Theule et al 2013)), involving desorption from silicate and carbon surfaces (Ulbricht et al 2006;Thrower et al 2009;Noble et al 2012a;Noble et al 2012b;Clemens et al 2013;Smith et al 2014;Doronin et al 2015;Suhasaria, Thrower, & Zacharias 2015;Smith, May, & Kay 2016;Suhasaria, Thrower, & Zacharias 2017;Potapov, Jäger, & Henning 2018a). The majority of these studies are devoted to the TPD of pure ices or binary mixtures, however, interstellar and circumstellar ices are more complex.…”

Dust/ice mixing in cold regions and solid-state water in the diffuse interstellar medium

“…In addition to these studies, there are studies on physical-chemical processes, such as formation, desorption, and diffusion of molecules, on the surface of cosmic dust analogues: amorphous carbon grains, atomic carbon foils, graphite, amorphous silica, and amorphous and crystalline silicate grains. The reader can find examples of and references to these experimental studies in recent papers [4][5][6][7][8][9] .Concerning ice-mixed-with-dust, this is a new direction of research started very recently by us [10][11][12] . One of the conclusions of our previous study of the optical constants of dust/ice mixtures 11 was that differences between measured constants and constants calculated using effective medium approaches show that a mathematical mixing (averaging) of the optical constants of water ice and silicates for the determination of the optical properties of silicate/ice mixtures can lead to incorrect results.…”

“…In addition to these studies, there are studies on physical-chemical processes, such as formation, desorption, and diffusion of molecules, on the surface of cosmic dust analogues: amorphous carbon grains, atomic carbon foils, graphite, amorphous silica, and amorphous and crystalline silicate grains. The reader can find examples of and references to these experimental studies in recent papers [4][5][6][7][8][9] .…”