SOFT X-RAY IRRADIATION OF METHANOL ICE: IMPLICATION FOR H
                    <sub>2</sub>
                    CO FORMATION IN INTERSTELLAR REGIONS

Ciaravella, A.; Muñoz, G. M.; Escobar, Antonio Jimenez; Cecchi‐Pestellini, C.; Giarrusso, S.; Barbera, Marco; Collura, A.

doi:10.1088/2041-8205/722/1/l45

Cited by 19 publications

(17 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…There are very few astrochemistry ice experiments that directly compare the effects of VUV and higher energy photons on ice chemistry. One exception is a study on soft X-ray and VUV dissociation of CH 3 OH ice into H 2 CO, 195 where a 8 K CH 3 OH ice was irradiated with 0.3 keV soft X-rays under UHV conditions. The X-ray flux was low and the total dose for the experiment was only 10 −6 photons molecule −1 .…”

Section: Uv Vs X-raysmentioning

confidence: 99%

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

2016

View full text Add to dashboard Cite

The interstellar medium is characterized by a rich and diverse chemistry. Many of its complex organic molecules are proposed to form through radical chemistry in icy grain mantles.Radicals form readily when interstellar ices (composed of water and other volatiles) are exposed to UV photons and other sources of dissociative radiation, and if sufficiently mobile the radicals can react to form larger, more complex molecules. The resulting complex organic molecules (COMs) accompany star and planet formation, and may eventually seed the origins of life on nascent planets. Experiments of increasing sophistication have demonstrated that known interstellar COMs as well as the prebiotically interesting amino acids can form through ice photochemistry. We review these experiments and discuss the qualitative and quantitative kinetic and mechanistic constraints they have provided. We finally compare the effects of UV radiation with those of three other potential sources of radical production and chemistry in interstellar ices: electrons, ions and X-rays.

show abstract

Section: Uv Vs X-raysmentioning

confidence: 99%

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

2016

View full text Add to dashboard Cite

show abstract

“…We include the photodestruction of grain mantle material by UV photons, X-rays, and cosmic rays (Ruffle & Herbst 2001). Experiments have shown that the irradiation of interstellar ice analogs by UV and X-ray photons induces chemistry in the ice (see, e.g., Hagen et al 1979;D'Hendecourt et al 1986;Allamandola et al 1988;Oberg et al 2010b;Ciaravella et al 2010). We adopt the equivalent gas-phase photorates for ice species and allow the products to remain on the grain to take part in further grain-surface reactions.…”

Section: Chemical Modelmentioning

confidence: 99%

Molecular Line Emission From a Protoplanetary Disk Irradiated Externally by a Nearby Massive Star

Walsh

Millar

Nomura

2013

ApJ

View full text Add to dashboard Cite

Star formation often occurs within or nearby stellar clusters. Irradiation by nearby massive stars can photoevaporate protoplanetary disks around young stars (so-called proplyds) which raises questions regarding the ability of planet formation to take place in these environments. We investigate the two-dimensional physical and chemical structure of a protoplanetary disk surrounding a low-mass (T Tauri) star which is irradiated by a nearby massive O-type star to determine the survivability and observability of molecules in proplyds. Compared with an isolated star-disk system, the gas temperature ranges from a factor of a few (in the disk midplane) to around two orders of magnitude (in the disk surface) higher in the irradiated disk. Although the UV flux in the outer disk, in particular, is several orders of magnitude higher, the surface density of the disk is sufficient for effective shielding of the disk midplane so that the disk remains predominantly molecular in nature. We also find that non-volatile molecules, such as HCN and H 2 O, are able to freeze out onto dust grains in the disk midplane so that the formation of icy planetesimals, e.g., comets, may also be possible in proplyds. We have calculated the molecular line emission from the disk assuming LTE and determined that multiple transitions of atomic carbon, CO (and isotopologues, 13 CO and C 18 O), HCO + , CN, and HCN may be observable with ALMA, allowing characterization of the gas column density, temperature, and optical depth in proplyds at the distance of Orion (≈400 pc).

show abstract

“…Despite the importance for prebiotic chemistry, very few studies have been performed using soft X-rays (e.g., Ciaravella et al 2010;Andrade et al 2010). Unlike UV photolysis where the energy is released in a single photodestruction event, the interaction of ices with X-rays is a multistep process.…”

Section: Introductionmentioning

confidence: 99%

Soft X-Ray Irradiation of Methanol Ice: Formation of Products as a Function of Photon Energy

Chen

Ciaravella

Muñoz

et al. 2013

ApJ

Self Cite

View full text Add to dashboard Cite

Pure methanol ices have been irradiated with monochromatic soft X-rays of 300 and 550 eV close to the 1s resonance edges of C and O, respectively, and with a broadband spectrum (250-1200 eV). The infrared (IR) spectra of the irradiated ices show several new products of astrophysical interest such as CH 2 OH, H 2 CO, CH 4 , HCOOH, HCOCH 2 OH, CH 3 COOH, CH 3 OCH 3 , HCOOCH 3 , and (CH 2 OH) 2 , as well as HCO, CO, and CO 2 . The effect of X-rays is the result of the combined interactions of photons and electrons with the ice. A significant contribution to the formation and growth of new species in the CH 3 OH ice irradiated with X-rays is given by secondary electrons, whose energy distribution depends on the energy of X-ray photons. Within a single experiment, the abundances of the new products increase with the absorbed energy. Monochromatic experiments show that product abundances also increase with the photon energy. However, the abundances per unit energy of newly formed species show a marked decrease in the broadband experiment as compared to irradiations with monochromatic photons, suggesting a possible regulatory role of the energy deposition rate. The number of new molecules produced per absorbed eV in the X-ray experiments has been compared to those obtained with electron and ultraviolet (UV) irradiation experiments.

show abstract

SOFT X-RAY IRRADIATION OF METHANOL ICE: IMPLICATION FOR H ₂ CO FORMATION IN INTERSTELLAR REGIONS

Cited by 19 publications

References 15 publications

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

Molecular Line Emission From a Protoplanetary Disk Irradiated Externally by a Nearby Massive Star

Soft X-Ray Irradiation of Methanol Ice: Formation of Products as a Function of Photon Energy

Contact Info

Product

Resources

About

SOFT X-RAY IRRADIATION OF METHANOL ICE: IMPLICATION FOR H 2 CO FORMATION IN INTERSTELLAR REGIONS

Cited by 19 publications

References 15 publications

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

Molecular Line Emission From a Protoplanetary Disk Irradiated Externally by a Nearby Massive Star

Soft X-Ray Irradiation of Methanol Ice: Formation of Products as a Function of Photon Energy

Contact Info

Product

Resources

About

SOFT X-RAY IRRADIATION OF METHANOL ICE: IMPLICATION FOR H ₂ CO FORMATION IN INTERSTELLAR REGIONS