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Publications (10 of 76) Show all publications
Kopacz, N., Csuka, J., Baqué, M., Iakubivskyi, I., Guðlaugardóttir, H., Klarenberg, I. J., . . . Geppert, W. (2022). A Study in Blue: Secondary Copper-Rich Minerals and Their Associated Bacterial Diversity in Icelandic Lava Tubes. Earth and Space Science, 9(5), Article ID e2022EA002234.
Open this publication in new window or tab >>A Study in Blue: Secondary Copper-Rich Minerals and Their Associated Bacterial Diversity in Icelandic Lava Tubes
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2022 (English)In: Earth and Space Science, E-ISSN 2333-5084, Vol. 9, no 5, article id e2022EA002234Article in journal (Refereed) Published
Abstract [en]

Lava tubes on Mars hold exciting potential for the preservation of biosignatures, which may survive on geological timescales in these isolated, stable environments. To support the development of future astrobiological mission concepts, we turn to terrestrial lava tubes, host to a variety of microbial communities and secondary minerals. Following a multidisciplinary sampling protocol, we retrieved biological, molecular, and mineralogical data from several lava tubes in Iceland. We report on blue-colored copper-rich secondary minerals and their associated bacterial communities using a multi-method approach, and an amalgam of 16S rRNA gene sequencing, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy data sets. We found numerous bacterial genera known for their high metal resistance and ability to survive in low-nutrient environments. Both are characteristics to be expected for any potential life in Martian lava tubes, and should be considered when checking for contaminants in Mars mission preparations. Associated with the microbial mats, we identified several types of copper-rich secondary minerals, indicating localized copper enrichments in the groundwater, possibly stemming from overlying ash deposits and nearby hyaloclastite formations. Molecular analysis revealed carotenoid signals preserved within the copper speleothems. If found in Martian lava tubes, blue copper-rich mineral precipitates would be deserving of astrobiological investigation, as they have potential to preserve biosignatures and harbor life.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-205141 (URN)10.1029/2022EA002234 (DOI)000797194500001 ()2-s2.0-85130781262 (Scopus ID)
Available from: 2022-05-31 Created: 2022-05-31 Last updated: 2022-11-14Bibliographically approved
Eklund, G., Kristiansson, M., Chartkunchand, K. C., Anderson, E. K., Simpson, M., Wester, R., . . . Geppert, W. D. (2022). Experimental lifetime of the a1Δ electronically excited state of CH−. Physical Review Research, 4(1), Article ID L012016.
Open this publication in new window or tab >>Experimental lifetime of the a1Δ electronically excited state of CH
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2022 (English)In: Physical Review Research, E-ISSN 2643-1564, Vol. 4, no 1, article id L012016Article in journal (Refereed) Published
Abstract [en]

By repeatedly probing the a1Δ excited state and the X3Σ ground-state populations in a beam of CH ions stored in a cryogenic ion-beam storage ring for 100 s, we extract an intrinsic lifetime of 14.9±0.5 s for this excited state. This is far longer than all earlier experimental and theoretical results, exposing large difficulties in measuring and calculating slow decays and the need for benchmark quality experiments.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:su:diva-204279 (URN)10.1103/physrevresearch.4.l012016 (DOI)000788801100001 ()2-s2.0-85125657209 (Scopus ID)
Funder
Swedish Research Council, 2017-00621Swedish Research Council, 2019-04379Swedish Research Council, 2020-03437Swedish Research Council, 2018-04092Swedish Research Council, 2019-04332Knut and Alice Wallenberg Foundation, 2018.0028
Available from: 2022-04-28 Created: 2022-04-28 Last updated: 2022-05-18Bibliographically approved
Rodriguez, S., Vinatier, S., Cordier, D., Tobie, G., Achterberg, R. K., Anderson, C. M., . . . West, R. A. (2022). Science goals and new mission concepts for future exploration of Titan's atmosphere, geology and habitability: titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON). Experimental astronomy, 54(2-3), 911-973
Open this publication in new window or tab >>Science goals and new mission concepts for future exploration of Titan's atmosphere, geology and habitability: titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON)
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2022 (English)In: Experimental astronomy, ISSN 0922-6435, E-ISSN 1572-9508, Vol. 54, no 2-3, p. 911-973Article in journal (Refereed) Published
Abstract [en]

In response to ESA’s “Voyage 2050” announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn’s largest moon Titan. Titan, a “world with two oceans”, is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan’s remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a “heavy” drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan’s northern latitudes with an orbiter and in situ element(s) would be highly complementary in terms of timing (with possible mission timing overlap), locations, and science goals with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan’s equatorial regions, in the mid-2030s. 

Keywords
Titan, Atmosphere, Geology, Habitability, Orbiter, Lake lander, Drones
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-202071 (URN)10.1007/s10686-021-09815-8 (DOI)000741251600001 ()2-s2.0-85122732674 (Scopus ID)
Available from: 2022-02-11 Created: 2022-02-11 Last updated: 2024-01-17Bibliographically approved
Tan, G. K., Simpson, A., Holtzen, S., Amador, E., Cable, M. L., Cantrell, T., . . . Stockton, A. M. (2022). Spatial Variation in Results of Biosignature Analyses of Apparently Homogeneous Samples from Mars Analogue Environments in Iceland. ACS Earth and Space Chemistry, 6(6), 1472-1481
Open this publication in new window or tab >>Spatial Variation in Results of Biosignature Analyses of Apparently Homogeneous Samples from Mars Analogue Environments in Iceland
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2022 (English)In: ACS Earth and Space Chemistry, E-ISSN 2472-3452, Vol. 6, no 6, p. 1472-1481Article in journal (Refereed) Published
Abstract [en]

The search for signs of life on Mars and beyond is time consuming and labor-intensive; hence, it is critical to understand how to design sampling strategies that can maximize the likelihood of success. Two distinct Mars analogue environments in Iceland were selected to represent volcanic resurfacing and glacial environments where characterization of different biosignatures at various spatial scales (100 m, 10 m, 1 m, 10 cm) was performed. This study serves the twofold purposes of (1) understanding the different levels of biosignature distributions in these analogue environments and (2) the spatial distributions of biosignatures in these environments, with an overarching goal of drawing lessons from low biomass Mars analogue environments to inform the best sampling strategies for sample collection strategies on Mars. Our results show that samples should be collected for analysis at large (at least 100 m spacing) to capture most differences within an apparently homogeneous environment of the aged resurfaced volcanic region like Mælifellssandur, whereas a smaller spacing at 10 m scale is necessary for younger glacial–volcanic environments like Fimmvörduháls. This study also illustrates the importance of understanding the variability across spatial scales in sampling design for future planetary missions.

Keywords
biosignatures, astrobiology, field studies, Iceland, volcanic sediments
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-208095 (URN)10.1021/acsearthspacechem.1c00390 (DOI)000813464900001 ()2-s2.0-85131661971 (Scopus ID)
Available from: 2022-08-19 Created: 2022-08-19 Last updated: 2022-11-15Bibliographically approved
Sundelin, D., Marimuthu, A. N., Thorwirth, S., Brünken, S. & Geppert, W. D. (2022). Spectroscopic characterisation of the isomeric H2NCH+ and H2CNH+ radical cations. Journal of Molecular Spectroscopy, 387, Article ID 111640.
Open this publication in new window or tab >>Spectroscopic characterisation of the isomeric H2NCH+ and H2CNH+ radical cations
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2022 (English)In: Journal of Molecular Spectroscopy, ISSN 0022-2852, E-ISSN 1096-083X, Vol. 387, article id 111640Article in journal (Refereed) Published
Abstract [en]

The vibrational transitions and the relative abundances of the two isomeric ions H2CNH+ and H2NCH+ generated through electron impact ionisation have been investigated in a noble gas tagging experiment. It could be shown that both species were formed with an abundance of 70 and 30% for H2NCH+ and H2CNH+, respectively. The obtained vibrational bands of the two species have been assigned to vibrational transitions through comparison with the results of ab initio calculations. These computations also predict both species to be moderately polar. The present investigations show that both isomers should be included in chemical model calculations of dark interstellar clouds, protoplanetary disks, star-forming regions as well as planetary atmospheres.

Keywords
Astrochemistry, Molecular ions, Cryogenic ion trap, Titan, Vibrational spectra
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-207948 (URN)10.1016/j.jms.2022.111640 (DOI)000827553200001 ()2-s2.0-85133462106 (Scopus ID)
Available from: 2022-08-19 Created: 2022-08-19 Last updated: 2022-11-15Bibliographically approved
Richardson, V., Ascenzi, D., Sundelin, D., Alcaraz, C., Romanzin, C., Thissen, R., . . . Geppert, W. D. (2021). Experimental and Computational Studies on the Reactivity of Methanimine Radical Cation (H2CNH+•) and its Isomer Aminomethylene (HCNH2+•) With C2H2. Frontiers in Astronomy and Space Sciences, 8, Article ID 752376.
Open this publication in new window or tab >>Experimental and Computational Studies on the Reactivity of Methanimine Radical Cation (H2CNH+•) and its Isomer Aminomethylene (HCNH2+•) With C2H2
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2021 (English)In: Frontiers in Astronomy and Space Sciences, E-ISSN 2296-987X, Vol. 8, article id 752376Article in journal (Refereed) Published
Abstract [en]

Experimental and theoretical studies are presented on the reactivity of the radical cation isomers H2CNH+• (methanimine) and HCNH2+• (aminomethylene) with ethyne (C2H2). Selective isomer generation is performed via dissociative photoionization of suitable neutral precursors as well as via direct photoionization of methanimine. Reactive cross sections (in absolute scales) and product branching ratios are measured as a function of photon and collision energies. Differences between isomers’ reactivity are discussed in light of ab-initio calculations of reaction mechanisms. The major channels, for both isomers, are due to H atom elimination from covalently bound adducts to give [C3NH4]+. Theoretical calculations show that while for the reaction of HCNH2+• with acetylene any of the three lowest energy [C3NH4]+ isomers can form via barrierless and exothermic pathways, for the H2CNH+• reagent the only barrierless pathway is the one leading to the production of protonated vinyl cyanide (CH2CHCNH+), a prototypical branched nitrile species that has been proposed as a likely intermediate in star forming regions and in the atmosphere of Titan. The astrochemical implications of the results are briefly addressed.

Keywords
methylene imine, acrylonitrile, vinyl cyanide, rate constant, cross sections, Titan, ISM, ion-molecule reactions
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-201888 (URN)10.3389/fspas.2021.752376 (DOI)000749439200001 ()
Available from: 2022-02-10 Created: 2022-02-10 Last updated: 2022-02-10Bibliographically approved
Sundelin, D., Ascenzi, D., Richardson, V., Alcaraz, C., Polášek, M., Romanzin, C., . . . Geppert, W. (2021). The reactivity of methanimine radical cation (H2CNH•+) and its isomer aminomethylene (HCNH2•+) with C2H4. Chemical Physics Letters, 777, Article ID 138677.
Open this publication in new window or tab >>The reactivity of methanimine radical cation (H2CNH•+) and its isomer aminomethylene (HCNH2•+) with C2H4
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2021 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 777, article id 138677Article in journal (Refereed) Published
Abstract [en]

Experimental and theoretical studies are presented on the reactivity of H2CNH'+ (methanimine) and HCNH2'+ (aminomethylene) with ethene (C2H4). Selective isomer generation is performed via dissociative photoionization of suitable neutral precursors and reactive cross sections and branching ratios are measured as a function of photon and collision energies. Differences between isomers' reactivity are discussed in light of ab-initio calculations on reaction mechanisms. The main products, for both isomers, are H-elimination, most likely occurring from covalently bound adducts (giving c-CH2CH2CHNH+/CH2NHCHCH2+) and H' atom transfer to yield H2CNH2+. The astrochemical implications of the results are briefly addressed.

Keywords
Interstellar medium, Rate constant, Astrochemistry molecular astrophysics, Isomerism, Protonated ketenimine, Ion-molecule reactions, Titan's atmosphere
National Category
Chemical Sciences Physical Sciences
Identifiers
urn:nbn:se:su:diva-195958 (URN)10.1016/j.cplett.2021.138677 (DOI)000662693000004 ()2-s2.0-85106251513 (Scopus ID)
Available from: 2021-08-30 Created: 2021-08-30 Last updated: 2022-11-11Bibliographically approved
Richardson, V., Alcaraz, C., Geppert, W., Polášek, M., Romanzin, C., Sundelin, D., . . . Ascenzi, D. (2021). The reactivity of methanimine radical cation (H2CNH.+) and its isomer aminomethylene (HCNH2.+) with methane. Chemical Physics Letters, 775, Article ID 138611.
Open this publication in new window or tab >>The reactivity of methanimine radical cation (H2CNH.+) and its isomer aminomethylene (HCNH2.+) with methane
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2021 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 775, article id 138611Article in journal (Refereed) Published
Abstract [en]

Experimental and theoretical studies are presented on the reactions of the isomeric radical cations H2CNH+ and HCNH2+ with CH4. Ionic isomers were generated selectively by VUV dissociative photoionization of azetidine and cyclopropylamine precursors respectively. Both exclusively give H2CNH2+ plus CH3 as products, but differences are observed related to a competition between stripping and complex-mediated H-transfer. Astrochemical implications for Titan’s atmosphere are briefly discussed, where the presence of methanimine (H2CNH), a key prebiotic molecule and a potential precursor for tholins, is proposed on the basis of atmospheric models and the observation of CH2NH2+ ions in Cassini mass spectrometric data.

Keywords
Interstellar medium, Rate constants, Ion-molecule reactions, Astrochemistry, Molecular astrophysics, Titan's atmosphere, Methane activation, Isomer, Methanimine, Aminomethylene
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-195709 (URN)10.1016/j.cplett.2021.138611 (DOI)000656477200002 ()2-s2.0-85104947990 (Scopus ID)
Available from: 2021-08-25 Created: 2021-08-25 Last updated: 2022-11-11Bibliographically approved
Neubeck, A., Broman, C., Ivarsson, M., Holm, N. G., Whitehouse, M., Nilsson, S., . . . Gervilla, F. (2020). Isotopic Signatures of Carbon in the 'Los Pobres' Graphite Mine, Ronda, Spain. Journal of Petrology, 61(4), Article ID egaa042.
Open this publication in new window or tab >>Isotopic Signatures of Carbon in the 'Los Pobres' Graphite Mine, Ronda, Spain
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2020 (English)In: Journal of Petrology, ISSN 0022-3530, E-ISSN 1460-2415, Vol. 61, no 4, article id egaa042Article in journal (Refereed) Published
Abstract [en]

Graphite formation temperatures in the ‘Los Pobres’ mine within the Ronda peridotite, Spain, previously reported to be between 770 and 820 °C, have been reinterpreted based on new temperature measurements using Raman spectroscopy. Additional in situ and bulk stable carbon isotopic measurements and fluid inclusion studies contributed to improved understanding of parts of the graphite formation process. Raman spectroscopy revealed that the formation of the ‘Los Pobres’ graphite extends to temperatures as low as 500 °C, indicating a broader temperature range than previously reported. Stable carbon isotopes and temperature estimates suggest two different crystallization events, followed by a late hydrothermal alteration of the host rock. The first event occurred at temperatures higher than ∼600°C, in which crystalline graphite was formed with a mixed 13C composition as a result of the mixing of two different carbon-bearing sources. The second graphite formation event took place below ∼600°C, within the same system, but with lower purity and crystallinity of the graphite. In the third event, the temperature decreased to less than 550 °C, and hydrothermal fluids altered the host rock, precipitating silica and iron oxides in veins penetrating both the host rock and the deposited graphite.

Keywords
Ronda peridotite, graphite formation temperature, Raman spectroscopy, carbon isotopes, fluid inclusions
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-191674 (URN)10.1093/petrology/egaa042 (DOI)000599215700002 ()
Available from: 2021-03-30 Created: 2021-03-30 Last updated: 2022-02-25Bibliographically approved
Marimuthu, A. N., Sundelin, D., Thorwirth, S., Redlich, B., Geppert, W. & Brünken, S. (2020). Laboratory gas-phase vibrational spectra of [C3H3]+ isomers and isotopologues by IRPD spectroscopy. Journal of Molecular Spectroscopy, 374, Article ID 111377.
Open this publication in new window or tab >>Laboratory gas-phase vibrational spectra of [C3H3]+ isomers and isotopologues by IRPD spectroscopy
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2020 (English)In: Journal of Molecular Spectroscopy, ISSN 0022-2852, E-ISSN 1096-083X, Vol. 374, article id 111377Article in journal (Refereed) Published
Abstract [en]

Gas phase vibrational spectra of [C3H3]+ isomers and their fully deuterated isotopologues measured in a cryogenic 22-pole ion trap are presented. The widely tunable free electron laser for infrared experiments, FELIX, was employed to cover the frequency range 500–2400 cm−1, complemented with an OPO/OPA system covering 2800–3400 cm−1. Spectral assignments for both the linear and cyclic isomeric form (H2C3H+ and c-C3H3+, respectively) are made based on various high-level computational studies. The effect of ion source conditions and different precursors (allene and propargyl chloride) for the preferential production of a specific isomer is discussed. The perturbation of the vibrational band position due to complexation with neon in the recorded infrared-predissociation (IRPD) spectra are also reported in this study.

Keywords
Astrochemistry, Molecular ions, Cryogenic ion trap, Titan, Vibrational spectra
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-191643 (URN)10.1016/j.jms.2020.111377 (DOI)000605622300001 ()
Available from: 2021-03-30 Created: 2021-03-30 Last updated: 2022-02-25Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-8452-181x

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