Heavy ion irradiation of crystalline water ice

Dartois, E.; Augé, B.; Boduch, P.; Brunetto, R.; Chabot, M.; Domaracka, A.; Ding, J. J.; Kamalou, O.; Lv, X. Y.; Rothard, H.; Silveira, E.F. da; Thomas, J. C.

doi:10.1051/0004-6361/201425415

Cited by 76 publications

(58 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Desorption is not, however, the only consequence from the interaction between cosmic rays and dust grains. In fact, recent experiments with interstellar ices (Dartois et al 2015) show that cosmic irradiation can also alter the ice mantle state on dust grains. The cosmic-ray reaction rates on grain surfaces, R CR (cm −3 s −1 ), are assumed to be the same as the rates for gas-phase reactions.…”

Section: Cosmic-ray Processes On Dust Grainsmentioning

confidence: 99%

Surface chemistry in photodissociation regions

Esplugues

Cazaux

Meijerink

et al. 2016

A&A

View full text Add to dashboard Cite

Context. The presence of dust can strongly affect the chemical composition of the interstellar medium. We model the chemistry in photodissociation regions (PDRs) using both gas-phase and dust-phase chemical reactions. Aims. Our aim is to determine the chemical compositions of the interstellar medium (gas/dust/ice) in regions with distinct (molecular) gas densities that are exposed to radiation fields with different intensities. Methods. We have significantly improved the Meijerink PDR code by including 3050 new gas-phase chemical reactions and also by implementing surface chemistry. In particular, we have included 117 chemical reactions occurring on grain surfaces covering different processes, such as adsorption, thermal desorption, chemical desorption, two-body reactions, photo processes, and cosmicray processes on dust grains. Results. We obtain abundances for different gas and solid species as a function of visual extinction, depending on the density and radiation field. We also analyse the rates of the formation of CO 2 and H 2 O ices in different environments. In addition, we study how chemistry is affected by the presence/absence of ice mantles (bare dust or icy dust) and the impact of considering different desorption probabilities. Conclusions. The type of substrate (bare dust or icy dust) and the probability of desorption can significantly alter the chemistry occurring on grain surfaces, leading to differences of several orders of magnitude in the abundances of gas-phase species, such as CO, H 2 CO, and CH 3 OH. The type of substrate, together with the density and intensity of the radiation field, also determine the threshold extinction to form ices of CO 2 and H 2 O. We also conclude that H 2 CO and CH 3 OH are mainly released into the gas phase of low, far-ultraviolet illuminated PDRs through chemical desorption upon two-body surface reactions, rather than through photodesorption.

show abstract

Section: Cosmic-ray Processes On Dust Grainsmentioning

confidence: 99%

Surface chemistry in photodissociation regions

Esplugues

Cazaux

Meijerink

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…Cook et al (2007) analysed possible mechanisms for surface renewal and also conclude that the presence of crystalline H 2 O ice and ammonia hydrates on the surface of Charon might be evidence of cryovolcanism. Nevertheless, crystalline H 2 O ice has been observed around young forming stars (Van Dishoeck 2004) and amply discussed by Suh & Kwon (2013) and Dartois et al (2015). Consequently, we cannot argue that the mere presence of crystalline H 2 O ice implies cryovolcanism.…”

Section: Discussionmentioning

confidence: 84%

(50000) Quaoar: Surface composition variability

Barucci

Ore

Perna

et al. 2015

A&A

View full text Add to dashboard Cite

Aims. The goal of this work is to investigate the composition of the surface of (50000) Quaoar and its spatial variability. Methods. We present new continuous spectra from the visible to near-IR (0.3−2.3 μm) obtained with the X-Shooter instrument at the VLT-ESO at four different epochs on the surface of Quaoar. The data represent the highest spectral resolution data ever obtained for this object and the first near-IR dataset acquired in a single exposure over the entire wavelength range. They are complemented by previously published photometric observations obtained in the near-IR (3.6, 4.5 μm) with the Spitzer Space Telescope, which provide an extra set of constraints in the model calculation. Spectral modelling was performed for the entire wavelength range by means of a code based on the Shkuratov radiative transfer formulation and of an updated value of albedo obtained from recent Herschel observations. Results. We obtained compositional information for different observed areas that can cover about 40% of the assumed rotational period of 8.84 h. Our analysis helps to prove the presence of CH 4 and C 2 H 6 , as previously reported, along with indications of the possible presence of NH 3 ·H 2 O. New evidence of N 2 is inferred from the shift in the CH 4 bands. The albedo at the two Spitzer bands suggests there may be CO diluted in N 2 , and CO 2 for one of the surface locations. Conclusions. The spectral similarities indicate the overall homogeneity of the surface composition of one hemisphere of Quaoar, while some subtle variations are apparent when modelling. The presence of NH 3 ·H 2 O would support the idea that Quaoar's surface may be relatively young.

show abstract

“…The deviation from the apparent pure destruction evolution measured for thick films, that is, when the number of molecules that is removed by sputtering becomes comparable or higher in importance than the bulk destruction of methanol, is best observed when the film becomes thinner, here for column densities below a few 10 16 cm −2 , as shown in the lower panel of Fig.2. The methanol sputtering yield can be calculated with the thinner ice experiment using a model similar to those used in Dartois et al (2015Dartois et al ( , 2018). An estimate is obtained by adjusting a fit that includes the electron sputtering for the thinner film and setting the previously determined destruction cross section to 5.45 ± 1.5 × 10 −13 cm 2 /ion.…”

Section: Pure Ch 3 Oh Thin and Thick Filmsmentioning

confidence: 99%

Non-thermal desorption of complex organic molecules

Dartois

Chabot

Bacmann

et al. 2020

A&A

Self Cite

View full text Add to dashboard Cite

The occurrence of complex organic molecules (COMs) in the gas phase at low temperature in the dense phases of the interstellar medium suggests that a non-thermal desorption mechanism is at work because otherwise, COMs should condense within a short timescale onto dust grains. Vacuum ultraviolet (UV) photodesorption has been shown to be much less efficient for complex organic molecules, such as methanol, because mostly photoproducts are ejected. The induced photolysis competes with photodesorption for large COMs, which considerably lowers the efficiency to desorb intact molecules. We pursue an experimental work that has already shown that water molecules, the dominant ice mantle species, can be efficiently sputtered by cosmic rays. We investigate the sputtering efficiency of complex organic molecules that are observed either in the ice mantles of interstellar dense clouds directly by infrared spectroscopy (CH 3 OH), or that are observed in the gas phase by millimeter telescopes (CH 3 COOCH 3 ) and that could be released from interstellar grain surfaces. We irradiated ice films containing complex organic molecules (methanol and methyl acetate) and water with swift heavy ions in the electronic sputtering regime. We monitored the infrared spectra of the film as well as the species released to the gas phase with a mass spectrometer. We demonstrate that when methanol or methyl acetate is embedded in a waterice mantle exposed to cosmic rays, a large portion is sputtered as an intact molecule, with a sputtering yield close to that of the main water-ice matrix. This must be even more true for the case of more volatile ice matrices, such as those that are embedded in carbon monoxide. Cosmic rays penetrating deep into dense clouds provide an efficient mechanism to desorb complex organic molecules. Compared to the VUV photons, which are induced by the interaction of cosmic rays, a large portion desorb as intact molecules with a proportion corresponding to the time-dependent bulk composition of the ice mantle, the latter evolving with time as a function of fluence due to the radiolysis of the bulk.

show abstract

Heavy ion irradiation of crystalline water ice

Cited by 76 publications

References 38 publications

Surface chemistry in photodissociation regions

Surface chemistry in photodissociation regions

(50000) Quaoar: Surface composition variability

Non-thermal desorption of complex organic molecules

Contact Info

Product

Resources

About