The Experts below are selected from a list of 4413 Experts worldwide ranked by ideXlab platform
P. Boduch - One of the best experts on this subject based on the ideXlab platform.
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cosmic ray Sputtering Yield of interstellar ice mantles co and co2 ice thickness dependence
2021Co-Authors: E Dartois, B. Augé, P. Boduch, Id T. Barkach, M Chabot, H Rothard, A N AgnihotriAbstract:Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions.
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Cosmic ray Sputtering Yield of interstellar ice mantles
2021Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, Hermann Rothard, Id T. Barkach, M Chabot, A N AgnihotriAbstract:Aims. Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions
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cosmic ray Sputtering Yield of interstellar h2o ice mantles ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, Id T. Barkach, M Chabot, A N Agnihotri, P. BoduchAbstract:Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by IR spectroscopy and mass spec- trometry, respectively. The Sputtering Yield is constant above a characteristic ice layer thickness and starts to decrease below this thickness. An estimate of the Sputtering depth corresponding to this length can be evaluated. In these experiments the measured desorption depth corresponds to 30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se). We expect that the desorption depth dependence varies with Se^a , where a=0.5. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Cosmic ray Sputtering Yield of interstellar H$_2$O ice mantles: Ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, M Chabot, A N Agnihotri, T. Id Barkach, P. BoduchAbstract:Aims. Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. Methods. The Sputtering Yields for swift ions simulating the effects of cosmic rays are most often measured in the semi-infinite limit using thick ice targets with the determination of the effective Yield per incident ion. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95 MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by infrared spectroscopy and mass spectrometry. Results. The Sputtering Yield is constant above a characteristic ice layer thickness and then starts to decrease below this thickness. An estimate of the typical Sputtering depth corresponding to this length can be evaluated by comparing the infinite thickness Yield to the column density where the onset of the Sputtering Yield decrease occurs. In these experiments the measured characteristic desorption depth corresponds to ≈30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se, deposited energy per unit path length). Considering the experiments on insulators, we expect that the desorption depth dependence varies with Seα, where α ~ 1. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Heavy ion irradiation of crystalline water ice - Cosmic ray amorphisation cross-section and Sputtering Yield
2015Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, J. J. Ding, X. Y. Lv, Martial Chabot, Omar Kamalou, Alicja Domaracka, Rosario Brunetto, Hermann RothardAbstract:Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice Sputtering Yield. Methods. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results. The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice Sputtering is measured on the infrared spectra, and the fitted Sputtering-Yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions. The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice Sputtering rates compete with the UV photodesorption Yields reported in the literature. The prevalence of direct cosmic ray Sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices.
Emmanuel Dartois - One of the best experts on this subject based on the ideXlab platform.
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Cosmic ray Sputtering Yield of interstellar ice mantles
2021Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, Hermann Rothard, Id T. Barkach, M Chabot, A N AgnihotriAbstract:Aims. Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions
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cosmic ray Sputtering Yield of interstellar h2o ice mantles ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, Id T. Barkach, M Chabot, A N Agnihotri, P. BoduchAbstract:Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by IR spectroscopy and mass spec- trometry, respectively. The Sputtering Yield is constant above a characteristic ice layer thickness and starts to decrease below this thickness. An estimate of the Sputtering depth corresponding to this length can be evaluated. In these experiments the measured desorption depth corresponds to 30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se). We expect that the desorption depth dependence varies with Se^a , where a=0.5. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Cosmic ray Sputtering Yield of interstellar H$_2$O ice mantles: Ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, M Chabot, A N Agnihotri, T. Id Barkach, P. BoduchAbstract:Aims. Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. Methods. The Sputtering Yields for swift ions simulating the effects of cosmic rays are most often measured in the semi-infinite limit using thick ice targets with the determination of the effective Yield per incident ion. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95 MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by infrared spectroscopy and mass spectrometry. Results. The Sputtering Yield is constant above a characteristic ice layer thickness and then starts to decrease below this thickness. An estimate of the typical Sputtering depth corresponding to this length can be evaluated by comparing the infinite thickness Yield to the column density where the onset of the Sputtering Yield decrease occurs. In these experiments the measured characteristic desorption depth corresponds to ≈30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se, deposited energy per unit path length). Considering the experiments on insulators, we expect that the desorption depth dependence varies with Seα, where α ~ 1. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Heavy ion irradiation of crystalline water ice - Cosmic ray amorphisation cross-section and Sputtering Yield
2015Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, J. J. Ding, X. Y. Lv, Martial Chabot, Omar Kamalou, Alicja Domaracka, Rosario Brunetto, Hermann RothardAbstract:Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice Sputtering Yield. Methods. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results. The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice Sputtering is measured on the infrared spectra, and the fitted Sputtering-Yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions. The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice Sputtering rates compete with the UV photodesorption Yields reported in the literature. The prevalence of direct cosmic ray Sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices.
A N Agnihotri - One of the best experts on this subject based on the ideXlab platform.
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cosmic ray Sputtering Yield of interstellar ice mantles co and co2 ice thickness dependence
2021Co-Authors: E Dartois, B. Augé, P. Boduch, Id T. Barkach, M Chabot, H Rothard, A N AgnihotriAbstract:Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions.
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Cosmic ray Sputtering Yield of interstellar ice mantles
2021Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, Hermann Rothard, Id T. Barkach, M Chabot, A N AgnihotriAbstract:Aims. Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions
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cosmic ray Sputtering Yield of interstellar h2o ice mantles ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, Id T. Barkach, M Chabot, A N Agnihotri, P. BoduchAbstract:Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by IR spectroscopy and mass spec- trometry, respectively. The Sputtering Yield is constant above a characteristic ice layer thickness and starts to decrease below this thickness. An estimate of the Sputtering depth corresponding to this length can be evaluated. In these experiments the measured desorption depth corresponds to 30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se). We expect that the desorption depth dependence varies with Se^a , where a=0.5. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Cosmic ray Sputtering Yield of interstellar H$_2$O ice mantles: Ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, M Chabot, A N Agnihotri, T. Id Barkach, P. BoduchAbstract:Aims. Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. Methods. The Sputtering Yields for swift ions simulating the effects of cosmic rays are most often measured in the semi-infinite limit using thick ice targets with the determination of the effective Yield per incident ion. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95 MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by infrared spectroscopy and mass spectrometry. Results. The Sputtering Yield is constant above a characteristic ice layer thickness and then starts to decrease below this thickness. An estimate of the typical Sputtering depth corresponding to this length can be evaluated by comparing the infinite thickness Yield to the column density where the onset of the Sputtering Yield decrease occurs. In these experiments the measured characteristic desorption depth corresponds to ≈30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se, deposited energy per unit path length). Considering the experiments on insulators, we expect that the desorption depth dependence varies with Seα, where α ~ 1. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
Hermann Rothard - One of the best experts on this subject based on the ideXlab platform.
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Cosmic ray Sputtering Yield of interstellar ice mantles
2021Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, Hermann Rothard, Id T. Barkach, M Chabot, A N AgnihotriAbstract:Aims. Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions
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cosmic ray Sputtering Yield of interstellar h2o ice mantles ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, Id T. Barkach, M Chabot, A N Agnihotri, P. BoduchAbstract:Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by IR spectroscopy and mass spec- trometry, respectively. The Sputtering Yield is constant above a characteristic ice layer thickness and starts to decrease below this thickness. An estimate of the Sputtering depth corresponding to this length can be evaluated. In these experiments the measured desorption depth corresponds to 30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se). We expect that the desorption depth dependence varies with Se^a , where a=0.5. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Cosmic ray Sputtering Yield of interstellar H$_2$O ice mantles: Ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, M Chabot, A N Agnihotri, T. Id Barkach, P. BoduchAbstract:Aims. Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. Methods. The Sputtering Yields for swift ions simulating the effects of cosmic rays are most often measured in the semi-infinite limit using thick ice targets with the determination of the effective Yield per incident ion. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95 MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by infrared spectroscopy and mass spectrometry. Results. The Sputtering Yield is constant above a characteristic ice layer thickness and then starts to decrease below this thickness. An estimate of the typical Sputtering depth corresponding to this length can be evaluated by comparing the infinite thickness Yield to the column density where the onset of the Sputtering Yield decrease occurs. In these experiments the measured characteristic desorption depth corresponds to ≈30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se, deposited energy per unit path length). Considering the experiments on insulators, we expect that the desorption depth dependence varies with Seα, where α ~ 1. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Heavy ion irradiation of crystalline water ice - Cosmic ray amorphisation cross-section and Sputtering Yield
2015Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, J. J. Ding, X. Y. Lv, Martial Chabot, Omar Kamalou, Alicja Domaracka, Rosario Brunetto, Hermann RothardAbstract:Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice Sputtering Yield. Methods. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results. The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice Sputtering is measured on the infrared spectra, and the fitted Sputtering-Yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions. The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice Sputtering rates compete with the UV photodesorption Yields reported in the literature. The prevalence of direct cosmic ray Sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices.
B. Augé - One of the best experts on this subject based on the ideXlab platform.
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cosmic ray Sputtering Yield of interstellar ice mantles co and co2 ice thickness dependence
2021Co-Authors: E Dartois, B. Augé, P. Boduch, Id T. Barkach, M Chabot, H Rothard, A N AgnihotriAbstract:Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions.
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Cosmic ray Sputtering Yield of interstellar ice mantles
2021Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, Hermann Rothard, Id T. Barkach, M Chabot, A N AgnihotriAbstract:Aims. Cosmic-ray-induced Sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray Sputtering. As was already done for water ice, we investigated the Sputtering Yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice Sputtering Yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion Sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the Sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions
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cosmic ray Sputtering Yield of interstellar h2o ice mantles ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, Id T. Barkach, M Chabot, A N Agnihotri, P. BoduchAbstract:Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by IR spectroscopy and mass spec- trometry, respectively. The Sputtering Yield is constant above a characteristic ice layer thickness and starts to decrease below this thickness. An estimate of the Sputtering depth corresponding to this length can be evaluated. In these experiments the measured desorption depth corresponds to 30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se). We expect that the desorption depth dependence varies with Se^a , where a=0.5. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Cosmic ray Sputtering Yield of interstellar H$_2$O ice mantles: Ice mantle thickness dependence
2018Co-Authors: Emmanuel Dartois, B. Augé, Hermann Rothard, Alicja Domaracka, M Chabot, A N Agnihotri, T. Id Barkach, P. BoduchAbstract:Aims. Interstellar grain mantles present in dense interstellar clouds are in constant exchange with the gas phase via accretion and desorption mechanisms such as UV, X-ray photodesorption, cosmic ray induced Sputtering, grain thermal fluctuations, and chemical reaction energy release. The relative importance of the various desorption mechanisms is of uttermost importance for astrophysical models to constrain the chemical evolution in such high density dense cloud regions. Methods. The Sputtering Yields for swift ions simulating the effects of cosmic rays are most often measured in the semi-infinite limit using thick ice targets with the determination of the effective Yield per incident ion. In this experimental work we investigated the Sputtering Yield as a function of ice mantle thickness, exposed to Xe ions at 95 MeV. The ion induced ice phase transformation and the Sputtering Yield were simultaneously monitored by infrared spectroscopy and mass spectrometry. Results. The Sputtering Yield is constant above a characteristic ice layer thickness and then starts to decrease below this thickness. An estimate of the typical Sputtering depth corresponding to this length can be evaluated by comparing the infinite thickness Yield to the column density where the onset of the Sputtering Yield decrease occurs. In these experiments the measured characteristic desorption depth corresponds to ≈30 ice layers. Assuming an effective cylindrical shape for the volume of sputtered molecules, the aspect ratio is close to unity; in the semi-infinite ice film case this ratio is the diameter to height of the cylinder. This result shows that most ejected molecules arise from a rather compact volume. The measured infinite thickness Sputtering Yield for water ice mantles scales as the square of the ion electronic stopping power (Se, deposited energy per unit path length). Considering the experiments on insulators, we expect that the desorption depth dependence varies with Seα, where α ~ 1. Astrophysical models should take into account the thickness dependence constraints of these ice mantles in the interface regions when ices are close to their extinction threshold. In the very dense cloud regions, most of the water ice mantles are above this limit for the bulk of the cosmic rays.
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Heavy ion irradiation of crystalline water ice - Cosmic ray amorphisation cross-section and Sputtering Yield
2015Co-Authors: Emmanuel Dartois, B. Augé, P. Boduch, J. J. Ding, X. Y. Lv, Martial Chabot, Omar Kamalou, Alicja Domaracka, Rosario Brunetto, Hermann RothardAbstract:Under cosmic irradiation, the interstellar water ice mantles evolve towards a compact amorphous state. Crystalline ice amorphisation was previously monitored mainly in the keV to hundreds of keV ion energies. Aims. We experimentally investigate heavy ion irradiation amorphisation of crystalline ice, at high energies closer to true cosmic rays, and explore the water-ice Sputtering Yield. Methods. We irradiated thin crystalline ice films with MeV to GeV swift ion beams, produced at the GANIL accelerator. The ice infrared spectral evolution as a function of fluence is monitored with in-situ infrared spectroscopy (induced amorphisation of the initial crystalline state into a compact amorphous phase). Results. The crystalline ice amorphisation cross-section is measured in the high electronic stopping-power range for different temperatures. At large fluence, the ice Sputtering is measured on the infrared spectra, and the fitted Sputtering-Yield dependence, combined with previous measurements, is quadratic over three decades of electronic stopping power. Conclusions. The final state of cosmic ray irradiation for porous amorphous and crystalline ice, as monitored by infrared spectroscopy, is the same, but with a large difference in cross-section, hence in time scale in an astrophysical context. The cosmic ray water-ice Sputtering rates compete with the UV photodesorption Yields reported in the literature. The prevalence of direct cosmic ray Sputtering over cosmic-ray induced photons photodesorption may be particularly true for ices strongly bonded to the ice mantles surfaces, such as hydrogen-bonded ice structures or more generally the so-called polar ices.
