Controlling the Morphology of Amorphous Solid Water

Stevenson, Kip P.; Kimmel, Greg A.; Dohnálek, Zdenek; Smith, R. Scott; Kay, Bruce D.

doi:10.1126/science.283.5407.1505

Cited by 394 publications

(397 citation statements)

References 30 publications

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“…The ice film grown this way in UHV is known to be amorphous in nature (ASW), while the deposition above 140 K results in crystalline ice (CW). 36,37 Alternatively, 50ML ASW (prepared by depositing water vapor at 110 K) was heated to 150 K and kept for 10 min to prepare crystalline water (CW). AA and FA films grown at 110 K are known to be amorphous in nature.…”

Section: Methodsmentioning

confidence: 99%

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Cyriac

Pradeep

2008

J. Phys. Chem. C

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In this paper, we investigated the interaction of simple carboxylic acids, formic acid (FA), acetic acid (AA), and propionic acid (PA) with thin layers of water ice in the temperature range of 110-190 K in ultrahigh vacuum. The focus, however, is on the AA-ice system. Molecularly thin layers of these systems were prepared on a pre-cooled polycrystalline copper substrate. The interactions and phase changes in the system were monitored with chemical sputtering using low-energy (e30 eV) Ar + , which probes the topmost surface layers. At 110 K, the deposited AA exists as dimers in its amorphous solid form. At the same temperature, in the presence of water ice, this dimeric form gets converted to chainlike oligomers. Chemical sputtering spectra show distinct features for these two surface species. The data suggest that ion formation reflects the surface structure, implying a unique mechanism for its formation. Detailed studies have been made with amorphous solid water (ASW) and crystalline water (CW) to get a complete understanding of the system. Experiments carried out with AA-D 2 O ice confirmed the proton-transfer mechanism during chemical sputtering. Other studies were conducted with AA-CH 3 OH and AA-CCl 4 systems. Detailed investigations performed to understand the effect of thickness of AA and ice overlayers suggest that the extent of water molecules required to effect the structural transformation in the acid is dependent on the amount of the latter. Dimeric-to-oligomeric transformation does not occur for the PA-ice system. Detection of a structural transition at the very top of ice in molecularly thin films adds additional capabilities to the low-energy ion scattering technique.

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Section: Methodsmentioning

confidence: 99%

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Cyriac

Pradeep

2008

J. Phys. Chem. C

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“…Background deposition of water vapor onto a cold surface results in highly porous ASW (Stevenson et al 1999;Kimmel et al 2001). After deposition, the ice morphology may change depending on external influences.…”

Section: Introductionmentioning

confidence: 99%

“…In a laboratory setting, the morphology of ASW depends on experimental conditions such as temperature, deposition rate and deposition direction of water molecules onto the substrate (Stevenson et al 1999;Kimmel et al 2001;Dohnalek et al 2003). Background deposition of water vapor onto a cold surface results in highly porous ASW (Stevenson et al 1999;Kimmel et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Thermal collapse of porous interstellar ice

Bossa

Isokoski

Valois

et al. 2012

A&A

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Aims. This article aims at a quantitative characterization of the phase transition of porous amorphous solid water (ASW) to a nonporous, i.e., more compact structure over an astronomically relevant temperature regime. Methods. A new laboratory based method is described that monitors the ice thickness decrease by combining optical interference with Fourier transform infrared spectroscopy. Three different water ice morphologies are studied; porous ASW as primary target, and less-porous ASW as well as crystalline solid water for comparison. Results. The thickness of the porous ASW sample is found to decrease by 12 ± 1% upon heating from 20 to 120 K. The thickness decrease of less-porous ASW is smaller, and negligible for crystalline solid water. Conclusions. Porous ASW, if formed under interstellar conditions, is expected to become less porous with increasing temperature. The thermally induced structural collapse affects the diffusion of the interstellar ice components, and therefore the catalytic properties of the ice.

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“…By comparing the amounts of surface areas of thin nc-ice and pc-ice films (thickness less than 250 bilayers) deposited at 22-145 K by effusive beam dosing at different incident angles and by ambient dosing, Stevenson et al showed that the surface area of the nc-ice deposits increases with a larger incident angle (from the normal direction) in qualitative accord with the predictions of the ballistic deposition model. 24 This model takes into general account of the interplay between roughening caused by randomness of deposition, smoothing by surface diffusion, and nonlocal effects generated by shadowing. 25 The unusually large values of apparent surface area obtained by ambient dosing at 22 K (2700 m 2 /g) and 77 K (640 m 2 /g) along with the linear increase of the surface area with deposition time led Stevenson et al to propose that the internal surface is directly connected to the external surface of the film.…”

Section: Introductionmentioning

confidence: 99%

Film Growth of Ice by Vapor Deposition at 128−185 K Studied by Fourier Transform Infrared Reflection−Absorption Spectroscopy: Evolution of the OH Stretch and the Dangling Bond with Film Thickness

Kanan

Leung

2002

J. Phys. Chem. B

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The polycrystalline and noncrystalline ice films vapor-deposited at 128-185 K were investigated by grazingangle Fourier transform Infrared Reflection-Absorption Spectroscopy (RAS). In particular, the polycrystalline ice phase was found above 155 K, whereas the noncrystalline phase was formed below 145 K. The nature of the polycrystalline and noncrystalline ice phases can be differentiated by comparing the respective RA spectra with spectral simulations based on the Fresnel reflection and Mie scattering methods. Furthermore, the OH stretching band (3800-2800 cm -1 ) exhibits complex behavior as a function of film thickness (from less than 10 nm to 1500 nm), which can be simulated and attributed primarily to the physics of absorption-reflection based on the Fresnel equations for reflection coefficients for parallel-and perpendicular-polarized light in a vacuum-dielectric film-metal system. The spectral evolution of the OH stretch with the film thickness is found to be similar for both polycrystalline and noncrystalline phases. In addition, spectral features of the incompletely coordinated OH groups at 3700-3690 cm -1 have been observed for a majority of noncrystalline and polycrystalline ice samples grown under different conditions (e.g., at 185 K), which shows that these OH dangling bonds are an integral part of the surfaces of both noncrystalline and polycrystalline ice phases. For thin films less than 200 nm thick, both kinds of ice are found to have a comparable amount of OH dangling bonds. In contrast, the thicker films (with thicknesses greater than 700 nm) of the noncrystalline phase contain a noticeably larger amount of OH dangling bonds than the polycrystalline films of comparable thickness. This thickness dependence of the OH dangling bond feature suggests that the OH dangling bonds are located most likely on the external surfaces of the crystalline grains and/or of the ice film itself at larger thicknesses for polycrystalline phase and on the tracery external surface in the case of noncrystalline phase.

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Controlling the Morphology of Amorphous Solid Water

Cited by 394 publications

References 30 publications

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Interaction of Carboxylic Acids and Water Ice Probed by Argon Ion Induced Chemical Sputtering

Thermal collapse of porous interstellar ice

Film Growth of Ice by Vapor Deposition at 128−185 K Studied by Fourier Transform Infrared Reflection−Absorption Spectroscopy: Evolution of the OH Stretch and the Dangling Bond with Film Thickness

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