scholarly journals Surface science investigations of the role of CO 2 in astrophysical ices

2013 ◽  
Vol 371 (1994) ◽  
pp. 20110578 ◽  
Author(s):  
John L. Edridge ◽  
Kati Freimann ◽  
Daren J. Burke ◽  
Wendy A. Brown
Keyword(s):  
Surface Science ◽  
Amorphous Solid ◽  
Temperature Programmed Desorption ◽  
Surface Data ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Temperature Programmed ◽  
Astrophysical Ices ◽  
Dust Grain ◽  
Science Investigations

We have recorded reflection–absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) data for a range of CO 2 -bearing model astrophysical ices adsorbed on a graphitic dust grain analogue surface. Data have been recorded for pure CO 2 , for CO 2 adsorbed on top of amorphous solid water, for mixed CO 2 :H 2 O ices and for CO 2 adsorbed on top of a mixed CH 3 OH:H 2 O ice. For the TPD data, kinetic parameters for desorption have been determined, and the trapping behaviour of the CO 2 in the H 2 O (CH 3 OH) ice has been determined. Data of these types are important as they can be used to model desorption in a range of astrophysical environments. RAIR spectra have also shown the interaction of the CO 2 with H 2 O and CH 3 OH and can be used to compare with astronomical observations, allowing the accurate assignment of spectra.

scholarly journals Impact of oxygen chemistry on model interstellar grain surfaces

2018 ◽  
Vol 20 (8) ◽  
pp. 5368-5376 ◽  
Author(s):  
A. Rosu-Finsen ◽  
M. R. S. McCoustra
Keyword(s):  
Infrared Spectroscopy ◽  
Molecular Oxygen ◽  
Amorphous Silica ◽  
Amorphous Solid ◽  
Temperature Programmed Desorption ◽  
Crystalline Solid ◽  
Amorphous Solid Water ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Solid Water ◽  
Temperature Programmed

Temperature-programmed desorption (TPD) and reflection–absorption infrared spectroscopy (RAIRS) are used to probe the effect of atomic and molecular oxygen (O and O2) beams on amorphous silica (aSiO2) and water (H2O) surfaces (porous-amorphous solid water; p-ASW, compact amorphous solid water; c-ASW, and crystalline solid water; CSW).

scholarly journals Using Surface Science Techniques to Investigate the Interaction of Acetonitrile with Dust Grain Analogue Surfaces

2021 ◽  
Author(s):  
Emily R. Ingman ◽  
Amber Shepherd ◽  
Wendy A. Brown
Keyword(s):  
Surface Science ◽  
Thermal Processing ◽  
Desorption Energy ◽  
Water Ice ◽  
Ice Surface ◽  
Coverage Analysis ◽  
Wide Range ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Temperature Programmed ◽  
Dust Grain

Surface science methodologies, such as reflection-absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD), are ideally suited to studying the interaction of molecules with model astrophysical surfaces. Here we describe the use of RAIRS and TPD to investigate the adsorption, interactions and thermal processing of acetonitrile and water containing model ices grown under astrophysical conditions on a graphitic dust grain analogue surface. Experiments show that acetonitrile physisorbs on the graphitic surface at all exposures. At the lowest coverages, repulsions between the molecules lead to a decreasing desorption energy with increasing coverage. Analysis of TPD data gives monolayer desorption energies ranging from 28.8 - 39.2 kJ mol-1 and an average multilayer desorption energy of 43.8 kJ mol-1. When acetonitrile is adsorbed in the presence of water ice, the desorption energy of monolayer acetonitrile shows evidence of desorption with a wide range of energies. An estimate of the desorption energy of acetonitrile from CI shows that it is increased to ~37 kJ mol-1 at the lowest exposures of acetonitrile. Amorphous water ice also traps acetonitrile on the graphite surface past its natural desorption temperature, leading to volcano and co-desorption. RAIRS data show that the C≡N vibration shifts, indicative of an interaction between the acetonitrile and the water ice surface.

scholarly journals Formation of interstellar propanal and 1-propanol ice: a pathway involving solid-state CO hydrogenation

2019 ◽  
Vol 627 ◽  
pp. A1 ◽  
Author(s):  
D. Qasim ◽  
G. Fedoseev ◽  
K.-J. Chuang ◽  
V. Taquet ◽  
T. Lamberts ◽  
...  
Keyword(s):  
Solid State ◽  
Co Hydrogenation ◽  
Theoretical Calculations ◽  
Interstellar Space ◽  
Activation Barriers ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Core Phase ◽  
Temperature Programmed ◽  
Freeze Out

Context. 1-propanol (CH3CH2CH2OH) is a three carbon-bearing representative of the primary linear alcohols that may have its origin in the cold dark cores in interstellar space. To test this, we investigated in the laboratory whether 1-propanol ice can be formed along pathways possibly relevant to the prestellar core phase. Aims. We aim to show in a two-step approach that 1-propanol can be formed through reaction steps that are expected to take place during the heavy CO freeze-out stage by adding C2H2 into the CO + H hydrogenation network via the formation of propanal (CH3CH2CHO) as an intermediate and its subsequent hydrogenation. Methods. Temperature programmed desorption-quadrupole mass spectrometry (TPD-QMS) was used to identify the newly formed propanal and 1-propanol. Reflection absorption infrared spectroscopy (RAIRS) was used as a complementary diagnostic tool. The mechanisms that can contribute to the formation of solid-state propanal and 1-propanol, as well as other organic compounds, during the heavy CO freeze-out stage are constrained by both laboratory experiments and theoretical calculations. Results. Here it is shown that recombination of HCO radicals formed upon CO hydrogenation with radicals formed via C2H2 processing – H2CCH and H3CCH2 – offers possible reaction pathways to solid-state propanal and 1-propanol formation. This extends the already important role of the CO hydrogenation chain to the formation of larger complex organic molecules. The results are compared with ALMA observations. The resulting 1-propanol:propanal ratio concludes an upper limit of <0.35−0.55, which is complemented by computationally derived activation barriers in addition to the experimental results.

Adsorption and reaction pathways of a chiral probe molecule, S-glycidol on a Pd(111) surface

2015 ◽  
Vol 5 (2) ◽  
pp. 738-742 ◽  
Author(s):  
Mausumi Mahapatra ◽  
Wilfred T. Tysoe
Keyword(s):  
Infrared Spectroscopy ◽  
Reaction Pathway ◽  
Temperature Programmed Desorption ◽  
Reaction Pathways ◽  
Probe Molecule ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Temperature Programmed

The chemistry of S-glycidol is studied on a Pd(111) surface using temperature-programmed desorption and reflection–absorption infrared spectroscopy to explore its suitability as a chiral probe molecule and to follow its reaction pathway.

scholarly journals Variation of the sticking of methanol on low-temperature surfaces as a possible obstacle to freeze out in dark clouds

2020 ◽  
Vol 494 (3) ◽  
pp. 4119-4129
Author(s):  
K A K Gadallah ◽  
A Sow ◽  
E Congiu ◽  
S Baouche ◽  
F Dulieu
Keyword(s):  
Low Temperature ◽  
Surface Temperature ◽  
Gas Phase ◽  
Amorphous Solid ◽  
Vacuum System ◽  
Initial Value ◽  
Water Ice ◽  
Dark Clouds ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Temperature Programmed

ABSTRACT Sticking of gas-phase methanol on different cold surfaces – gold, 13CO, and amorphous solid water (ASW) ice – was studied as a function of surface temperature (7–40 K). In an ultrahigh-vacuum system, reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption methods were simultaneously used to measure methanol sticking efficiency. Methanol band strengths obtained by RAIRS vary greatly depending on the type of the surface. Nevertheless, both methods indicate that the sticking of methanol on different surfaces varies with surface temperature. The sticking efficiency decreases by 30${{\ \rm per\ cent}}$ as the surface temperature goes from 7 to 16 K, then gradually increases until the temperature is 40 K, reaching approximately the initial value found at 7 K. The sticking of methanol differs slightly from one surface to another. At low temperature, it has the lowest values on gold, intermediate values on water ice, and the highest values are found on CO ice, although these differences are smaller than those observed with temperature variation. There exists probably a turning point during the structural organization of methanol ice at 16 K, which makes the capture of methanol from the gas phase less efficient. We wonder if this observation could explain the surprising high abundance of gaseous methanol observed in dense interstellar cores, where it should accrete on grains. In this regard, a 30${{\ \rm per\ cent}}$ reduction of the sticking is not sufficient in itself but transposed to astrophysical conditions dominated by cold gas (∼15 K), which could reduce the sticking efficiency by two orders of magnitude.

KINETIC AND REACTIVE PROPERTIES OF ETHYLENE ON CLEAN AND HYDROGEN-COVERED Pd(111)

2003 ◽  
Vol 10 (06) ◽  
pp. 909-916 ◽  
Author(s):  
L. BURKHOLDER ◽  
D. STACCHIOLA ◽  
W. T. TYSOE
Keyword(s):  
Activation Energy ◽  
Infrared Spectroscopy ◽  
Temperature Programmed Desorption ◽  
Molecular Adsorption ◽  
Lateral Interactions ◽  
Ethylene Adsorption ◽  
Reflection Absorption Infrared Spectroscopy ◽  
Temperature Programmed ◽  
Ethane Formation ◽  
Reactive Properties

Several molecular adsorption states are identified following ethylene adsorption on clean and hydrogen-covered Pd(111) using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). Di-σ-bonded ethylene forms on clean Pd(111) desorbing with an activation energy of 80 kJ/mol at low coverages. The strong intermolecular lateral interactions considerably reduce the desorption temperature at higher coverages. Π-bonded ethylene is formed on hydrogen-covered Pd(111), where the proportion of π-bonded species increases with hydrogen coverage. This species converts to the more stable di-σ-bonded species on heating. Ethane formation is detected in TPD from hydrogen-precovered Pd(111), which is predominantly formed by reaction with π-bonded ethylene.

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