Comparative electron irradiations of amorphous and crystalline astrophysical ice analogues

Mifsud, Duncan V.; Hailey, Perry A.; Herczku, Péter; Sulik, B.; Juhász, Zoltán; Kovács, Sándor; Kaňuchová, Z.; Ioppolo, Sergio; McCullough, Robert; Paripás, Béla; Mason, Nigel J.

doi:10.1039/d2cp00886f

Cited by 9 publications

(22 citation statements)

References 84 publications

(203 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar trends for O 2 and H 2 production were observed by Zheng et al who made use of quadrupole mass spectrometry to detect the formation of these products in electron irradiated ASW and Ic [45]. Such results are further evidence that the phase and structural morphology of an astrophysical ice analogue has a direct influence on its radiolytic chemical productivity [45,46].…”

Section: Comparative H 2 O 2 Productivitiessupporting

confidence: 81%

“…Our work therefore represents a progression in our understanding of the phase dependence of the radiation physics and chemistry of H 2 O astrophysical ices, thus allowing this parameter to be better incorporated into more exhaustive and relevant future experiments performed using a systems astrochemistry approach [47]. We have also interpreted our results in light of the new conclusions presented by Mifsud et al with regards to the role of hydrogen-bonds in impeding the radiolytic decay of crystalline ices [46].…”

Section: Introductionmentioning

confidence: 56%

“…In Ic and Ih, this hydrogen-bonding network extends throughout the entirety of the crystal lattice and thus adds an extra element of stability to the structure. During electron irradiation, a portion of the incident electron's kinetic energy must be expended upon overcoming the stabilising effect of hydrogen-bonding before radiolytic dissociation of the H 2 O molecule may take place [46]. Such a disruption would result in a localised amorphization characterised by increased ice defects (such as Bjerrum defects), as evidenced by the spectra presented in Fig.…”

Section: Comparative H 2 O 2 Productivitiesmentioning

confidence: 99%

“…Our recent experimental work studying the comparative 2 keV electron irradiation of amorphous and crystalline methanol (CH 3 OH) and nitrous oxide (N 2 O) ices at 20 K has also revealed a greater chemical productivity in irradiated amorphous solids [46]. However, that work additionally demonstrated the role of hydrogenbonding in controlling the radiolytic decay of a molecular solid: crystalline solids which exhibit extensive arrays of hydrogen-bonds are more resistant to radiolytic decay than are their amorphous counterparts, thus providing fewer radicals for the formation of new products.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Laboratory experiments on the radiation astrochemistry of water ice phases

et al. 2022

Self Cite

View full text Add to dashboard Cite

Water (H2O) ice is a ubiquitous component of the universe, having been detected in a variety of interstellar and Solar System environments where radiation plays an important role in its physico-chemical transformations. Although the radiation chemistry of H2O astrophysical ice analogues has been well studied, direct and systematic comparisons of different solid phases are scarce and are typically limited to just two phases. In this article, we describe the results of an in-depth study of the 2 keV electron irradiation of amorphous solid water (ASW), restrained amorphous ice (RAI) and the cubic (Ic) and hexagonal (Ih) crystalline phases at 20 K so as to further uncover any potential dependence of the radiation physics and chemistry on the solid phase of the ice. Mid-infrared spectroscopic analysis of the four investigated H2O ice phases revealed that electron irradiation of the RAI, Ic, and Ih phases resulted in their amorphization (with the latter undergoing the process more slowly) while ASW underwent compaction. The abundance of hydrogen peroxide (H2O2) produced as a result of the irradiation was also found to vary between phases, with yields being highest in irradiated ASW. This observation is the cumulative result of several factors including the increased porosity and quantity of lattice defects in ASW, as well as its less extensive hydrogen-bonding network. Our results have astrophysical implications, particularly with regards to H2O-rich icy interstellar and Solar System bodies exposed to both radiation fields and temperature gradients. Graphical abstract

show abstract

Section: Comparative H 2 O 2 Productivitiessupporting

confidence: 81%

Section: Introductionmentioning

confidence: 56%

Section: Comparative H 2 O 2 Productivitiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Laboratory experiments on the radiation astrochemistry of water ice phases

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…Our recent work has also demonstrated that the solid phase of an irradiated ice plays a crucial role in determining the outcome of astrochemical reactions mediated by ionising radiation. Through a series of comparative electron irradiations, we have demonstrated that the radiolytic decay rate of an astrochemical ice is dependent upon the nature, strength, and extent of the intermolecular interactions that characterise its solid phase ( Mifsud et al, 2022b ; Mifsud et al, 2022c ). For instance, the decay rate of α-crystalline CH 3 OH was found to be significantly less rapid than that of the amorphous phase.…”

Section: Introductionmentioning

confidence: 99%

Energetic electron irradiations of amorphous and crystalline sulphur-bearing astrochemical ices

et al. 2022

Self Cite

View full text Add to dashboard Cite

Laboratory experiments have confirmed that the radiolytic decay rate of astrochemical ice analogues is dependent upon the solid phase of the target ice, with some crystalline molecular ices being more radio-resistant than their amorphous counterparts. The degree of radio-resistance exhibited by crystalline ice phases is dependent upon the nature, strength, and extent of the intermolecular interactions that characterise their solid structure. For example, it has been shown that crystalline CH3OH decays at a significantly slower rate when irradiated by 2 keV electrons at 20 K than does the amorphous phase due to the stabilising effect imparted by the presence of an extensive array of strong hydrogen bonds. These results have important consequences for the astrochemistry of interstellar ices and outer Solar System bodies, as they imply that the chemical products arising from the irradiation of amorphous ices (which may include prebiotic molecules relevant to biology) should be more abundant than those arising from similar irradiations of crystalline phases. In this present study, we have extended our work on this subject by performing comparative energetic electron irradiations of the amorphous and crystalline phases of the sulphur-bearing molecules H2S and SO2 at 20 K. We have found evidence for phase-dependent chemistry in both these species, with the radiation-induced exponential decay of amorphous H2S being more rapid than that of the crystalline phase, similar to the effect that has been previously observed for CH3OH. For SO2, two fluence regimes are apparent: a low-fluence regime in which the crystalline ice exhibits a rapid exponential decay while the amorphous ice possibly resists decay, and a high-fluence regime in which both phases undergo slow exponential-like decays. We have discussed our results in the contexts of interstellar and Solar System ice astrochemistry and the formation of sulphur allotropes and residues in these settings.

show abstract

Sulphur ion implantation into O2, CO, and CO2 ices: Implications for the formation of sulphur-bearing molecules in the Kuiper Belt

Mifsud,

Kaňuchová,

Herczku

et al. 2024

Icarus

View full text Add to dashboard Cite

Comparative electron irradiations of amorphous and crystalline astrophysical ice analogues

Abstract: We have irradiated the amorphous and crystalline phases of CH3OH and N2O astrophysical ice analogues using 2 keV electrons and have found that the decay rate is dependent upon the nature and extent of the intermolecular bonding in these solid phases.

Cited by 9 publications

References 84 publications

Laboratory experiments on the radiation astrochemistry of water ice phases

Laboratory experiments on the radiation astrochemistry of water ice phases

Energetic electron irradiations of amorphous and crystalline sulphur-bearing astrochemical ices

Sulphur ion implantation into O2, CO, and CO2 ices: Implications for the formation of sulphur-bearing molecules in the Kuiper Belt

Contact Info

Product

Resources

About