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The photo-induced desorption and oxidation of CO on Ru(0001) is simulated using ab initio molecular dynamics with electronic friction that accounts for the non-equilibrated excited electrons and phonons. Different (O,CO) coverages are…

Materials Science · Physics 2023-07-06 Auguste Tetenoire , J. Iñaki Juaristi , Maite Alducin

Although defects on graphene can degrade electron transport and its ability for use as a protection layer, they can also be helpful to tailor the local properties or activate new sites for particular adsorbates. Here, carbon vacancy defects…

Materials Science · Physics 2018-05-23 Tianbai Li , Jory A. Yarmoff

At low temperatures (10 K), hydrogen atoms can diffuse quickly on grain ice mantles and frequently encounter hydrogen molecules, which cover a notable fraction of grain surface. The desorption energy of H atoms on H2 substrates is much less…

Solar and Stellar Astrophysics · Physics 2021-03-31 Qiang Chang , Xuli Zheng , Xia Zhang , Donghui Quan , Yang Lu , Qingkuan Meng , Xiaohu Li , Long-Fei Chen

The deuterium enrichment in molecules in dark molecular cloud cores and starforming regions is usually attributed to gas-phase chemistry. Here we examine the effects of surface and mantle chemical reactions on the deuteration of species. We…

Astrophysics of Galaxies · Physics 2018-03-16 Juris Kalvans , Ivar Shmeld

We characterized CO2 adsorption and diffusion on the missing row reconstructed Cu(100)-O surface using a combination of scanning tunneling microscopy (STM) and density functional theory (DFT) calculations with dispersion. We deposited CO2…

Mesoscale and Nanoscale Physics · Physics 2020-07-14 Steven J. Tjung , Qiang Zhang , Jacob J. Repicky , Simuck F. Yuk , Xiaowa Nie , Nancy M. Santagata , Aravind Asthagiri , Jay A. Gupta

We present a general computational scheme based on molecular dynamics (m.d.) simulation for calculating the chemical potential of adsorbed molecules in thermal equilibrium on the surface of a material. The scheme is based on the calculation…

Statistical Mechanics · Physics 2009-11-13 D. Alfe` , M. J. Gillan

The interaction of CO with the Fe3O4(001)-(rt2xrt2)R45{\deg} surface was studied using temperature programmed desorption (TPD), scanning tunneling microscopy (STM) and x-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh…

The work is devoted to the adaptation of the results of laboratory studies of the laser-induced dissociation of molecules of benzene adsorbed on a quartz substrate to the conditions of the interstellar medium. Adsorption was performed under…

Astrophysics of Galaxies · Physics 2019-08-14 M. S. Murga , V. N. Varakin , A. V. Stolyarov , D. S. Wiebe

The HDO/H2O ratio in interstellar gas is often used to draw conclusions on the origin of water in star-forming regions and on Earth. In cold cores and in the outer regions of protoplanetary disks, gas-phase water comes from photodesorption…

Astrophysics of Galaxies · Physics 2015-03-11 Carina Arasa , Jesper Koning , Geert-Jan Kroes , Catherine Walsh , Ewine F. van Dishoeck

Understanding of the complex behavior of particles at surfaces requires detailed knowledge of both macroscopic and microscopic processes that take place; also certain processes depend critically on temperature and gas pressure. To link…

Materials Science · Physics 2009-10-31 C. Stampfl , H. J. Kreuzer , S. H. Payne , H. Pfnuer , M. Scheffler

We compute the desorption rate of icy mantles on dust grains as a function of the size and composition of both the grain and the mantle. We combine existing models of cosmic ray (CR) related desorption phenomena with a model of CR transport…

Astrophysics of Galaxies · Physics 2021-09-22 Kedron Silsbee , Paola Caselli , Alexei V. Ivlev

We consider binary liquid mixtures near their critical consolute points and exposed to geometrically flat but chemically structured substrates. The chemical contrast between the various substrate structures amounts to opposite local…

Soft Condensed Matter · Physics 2009-11-11 Monika Sprenger , Frank Schlesener , S. Dietrich

Only recently, the activation of oxygen molecules on clean defect-free transition metal oxide surfaces has been reported, for example on the CaO-terminated surface of the Ruddelsden-Popper perovskite \crosurf. In this work we show that…

Materials Science · Physics 2018-10-10 Wernfried Mayr-Schmölzer , Florian Mittendorfer , Josef Redinger

We report on a computational study of the clean and oxygen-covered Rh(110) surface, based on density-functional theory within the local-density approximation. We have used plane-wave basis sets and Vanderbilt ultra-soft pseudopotentials.…

Condensed Matter · Physics 2009-10-28 Kurt Stokbro , Stefano Baroni

We study the effects of grain surface reactions on the chemistry of protoplanetary disks where gas, ice surface layers and icy mantles of dust grains are considered as three distinct phases. Gas phase and grain surface chemistry is found to…

Astrophysics of Galaxies · Physics 2020-01-08 Maxime Ruaud , Uma Gorti

Using first-principles calculations, we systematically study the adsorption behavior of a single molecular H$_{2}$O on the Be(0001) surface. We find that the favored molecular adsorption site is the top site with an adsorption energy of…

Materials Science · Physics 2015-05-27 Shuang-Xi Wang , Peng Zhang , Jian Zhao , Shu-Shen Li , Ping Zhang

By performing first-principles molecular dynamics calculations, we systematically simulate the adsorption behavior of oxygen molecules on the clean and strained Pb(111) surfaces. The obtained molecular adsorption precursor state, and the…

Materials Science · Physics 2011-10-28 Yu Yang , Ping Zhang

Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. Especially, saturated, hydrogen-rich molecules are formed through surface chemistry.…

Astrophysics of Galaxies · Physics 2022-02-11 H. M. Cuppen , A. Fredon , T. Lamberts , E. M. Penteado , M. Simons , C. Walsh

Detailed semi-empirical interaction potential calculations are performed to determine the potential energy surface experienced by the molecules CO, HCN, H2O and H2CO, when adsorbed on the basal plane (0001) of graphite at low temperature.…

Chemical Physics · Physics 2015-05-13 Azzedine Lakhlifi , John P. Killingbeck

Using density-functional theory in combination with a thermodynamic formalism we calculate the relative stability of various structural models of the polar O-terminated (000-1)-O surface of ZnO. Model surfaces with different concentrations…

Materials Science · Physics 2009-11-10 B. Meyer