Glass Transition and Intermixing of Amorphous Water and Methanol

Souda, Ryūtarō

doi:10.1103/physrevlett.93.235502

Cited by 90 publications

(152 citation statements)

References 15 publications

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“…The TPD peak observed at 112 K in Fig. 2 can therefore be attributed to the desorption of OCS from the methanol ice as it undergoes a phase transition (Souda 2004), analogous to the trapping and release observed for OCS binary water ices.…”

Section: Resultsmentioning

confidence: 73%

The effects of methanol on the trapping of volatile ice components

Burke

Brown

2015

Monthly Notices of the Royal Astronomical Society

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The evaporation of icy mantles, which have been formed on the surface of dust grains, is acknowledged to give rise to the rich chemistry that has been observed in the vicinity of hot cores and corinos. It has long been established that water ice is the dominant species within many astrophysical ices. However, other molecules found within astrophysical ices, particularly methanol, can influence the desorption of volatile species from the ice. Here we present a detailed investigation of the adsorption and desorption of methanol-containing ices, showing the effect that methanol has on the trapping and release of volatiles from model interstellar ices. OCS and CO 2 have been used as probe molecules since they have been suggested to reside in water-rich and methanol-rich environments. Experiments show that methanol fundamentally changes the desorption characteristics of both OCS and CO 2 , leading to the observation of mainly codesorption of both species with bulk water ice for the tertiary ices and causing a lowering of the temperature of the volcano component of the desorption. In contrast, binary ices are dominated by standard volcano desorption. This observation clearly shows that codepositing astrophysically relevant impurities with water ice, such as methanol, can alter the desorption dynamics of volatiles that become trapped in the pores of the amorphous water ice during the sublimation process. Incorporating experimental data into a simple model to simulate these processes on astrophysical timescales shows that the additional methanol component releases larger amounts of OCS from the ice mantle at lower temperatures and earlier times. These results are of interest to astronomers as they can be used to model the star formation process, hence giving information about the evolution of our Universe.

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Section: Resultsmentioning

confidence: 73%

The effects of methanol on the trapping of volatile ice components

Burke

Brown

2015

Monthly Notices of the Royal Astronomical Society

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“…A large decrease in scattered ion intensity was observed in the 130-155 K window due to the desorption of CH 3 OH molecules. The desorption of methanol was visible as pressure increase in the vacuum gauge, starting at ∼130 K. Because of this, crystallization of methanol, supposed to occur at 120 K, 32 was indistinguishable. Moreover, we doubt whether the crystallization in methanol could be observable as a change in ion intensity since the crystallization of water ice was not reflected in ion intensities.…”

Section: Resultsmentioning

confidence: 99%

“…Vibrational spectroscopy, 15 electron diffraction, 10 X-ray absorption spectroscopy, 16 electron spectroscopy, 17 TPD, 18 Kelvin probe, 13 and secondary ion mass spectrometry (SIMS) 19 are some of the experimental techniques used to understand the physics and chemistry of ice. Several of these techniques have been employed to investigate surface structure and morphological changes of amorphous ice.…”

Section: Introductionmentioning

confidence: 99%

Structural Reorganization on Amorphous Ice Films below 120 K Revealed by Near-Thermal (∼1 eV) Ion Scattering

Cyriac

Pradeep

2008

J. Phys. Chem. C

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Topmost layers of amorphous ice undergo a structural transformation before the onset of crystallization and well before the premelting transitions. Ultralow-energy (∼1 eV) mass-selected Ar + scattering has been used to detect this structural change. The transformation is manifested in the form of drastic changes in the scattered ion intensity in the e2 eV collision energy range. The changes are limited to the first few monolayers as larger thicknesses produce no additional effects. The technique becomes chemically sensitive but insensitive to the morphology and structure as the energy is increased above 3 eV. A similar behavior is observed with He + , Kr + , and a polyatomic ion, CH 3 + . Experiments revealed that the structural changes occurred only on amorphous ice and no such change occurred on crystalline ice. H 2 O and D 2 O ices behave similarly.

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“…The results showed that the T g of vapor-deposited methanol films begins at 80 K, which is 23 K lower than its calorimetric T g (22). In addition to water and alcohol, n-alkanes with no apparent T g have also been studied.…”

Section: The Phase Transitionmentioning

confidence: 99%

“…Desorption of molecules from ice surfaces can be accompanied by processes in the surface that include diffusion (18)(19)(20)(21), molecular volcano (19), crystallization (22,23), and polymerization events, all of which have been the subjects of detailed studies. We can better understand the molecular details of processes taking place in such solids by using vibrational spectroscopy, which in conjunction with TPD is often an indispensable tool .…”

Section: Introductionmentioning

confidence: 99%

Probing Molecular Solids with Low-Energy Ions

Bag

Bhuin

Natarajan

et al. 2013

Annual Rev. Anal. Chem.

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Ion/surface collisions in the ultralow-to low-energy (1-100-eV) window represent an excellent technique for investigation of the properties of condensed molecular solids at low temperatures. For example, this technique has revealed the unique physical and chemical processes that occur on the surface of ice, versus the liquid and vapor phases of water. Such instrumentdependent research, which is usually performed with spectroscopy and mass spectrometry, has led to new directions in studies of molecular materials. In this review, we discuss some interesting results and highlight recent developments in the area. We hope that access to the study of molecular solids with extreme surface specificity, as described here, will encourage investigators to explore new areas of research, some of which are outlined in this review.

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Glass Transition and Intermixing of Amorphous Water and Methanol

Cited by 90 publications

References 15 publications

The effects of methanol on the trapping of volatile ice components

The effects of methanol on the trapping of volatile ice components

Structural Reorganization on Amorphous Ice Films below 120 K Revealed by Near-Thermal (∼1 eV) Ion Scattering

Probing Molecular Solids with Low-Energy Ions

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