| 1. |
- Albert, Damien, et al.
(author)
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A Decade with VAMDC : Results and Ambitions
- 2020
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In: Atoms. - : MDPI. - 2218-2004. ; 8:4
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Journal article (peer-reviewed)abstract
- This paper presents an overview of the current status of the Virtual Atomic and Molecular Data Centre (VAMDC) e-infrastructure, including the current status of the VAMDC-connected (or to be connected) databases, updates on the latest technological development within the infrastructure and a presentation of some application tools that make use of the VAMDC e-infrastructure. We analyse the past 10 years of VAMDC development and operation, and assess their impact both on the field of atomic and molecular (A&M) physics itself and on heterogeneous data management in international cooperation. The highly sophisticated VAMDC infrastructure and the related databases developed over this long term make them a perfect resource of sustainable data for future applications in many fields of research. However, we also discuss the current limitations that prevent VAMDC from becoming the main publishing platform and the main source of A&M data for user communities, and present possible solutions under investigation by the consortium. Several user application examples are presented, illustrating the benefits of VAMDC in current research applications, which often need the A&M data from more than one database. Finally, we present our vision for the future of VAMDC.
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| 2. |
- Cole, Theresa, et al.
(author)
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Ancient DNA of crested penguins: Testing for temporal genetic shifts in the world's most diverse penguin clade
- 2018
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In: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 131, s. 72-79
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Journal article (peer-reviewed)abstract
- Human impacts have substantially reduced avian biodiversity in many parts of the world, particularly on isolated islands of the Pacific Ocean. The New Zealand archipelago, including its five subantarctic island groups, holds breeding grounds for a third of the world's penguin species, including several representatives of the diverse crested penguin genus Eudyptes. While this species-rich genus has been little studied genetically, recent population estimates indicate that several Eudyptes taxa are experiencing demographic declines. Although crested penguins are currently limited to southern regions of the New Zealand archipelago, prehistoric fossil and archaeological deposits suggest a wider distribution during prehistoric times, with breeding ranges perhaps extending to the North Island. Here, we analyse ancient, historic and modern DNA sequences to explore two hypotheses regarding the recent history of Eudyptes in New Zealand, testing for (1) human-driven extinction of Eudyptes lineages; and (2) reduced genetic diversity in surviving lineages. From 83 prehistoric bone samples, each tentatively identified as ‘Eudyptes spp.’, we genetically identified six prehistoric penguin taxa from mainland New Zealand, including one previously undescribed genetic lineage. Moreover, our Bayesian coalescent analyses indicated that, while the range of Fiordland crested penguin (E. pachyrhynchus) may have contracted markedly over the last millennium, genetic DNA diversity within this lineage has remained relatively constant. This result contrasts with human-driven biodiversity reductions previously detected in several New Zealand coastal vertebrate taxa.
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| 3. |
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| 4. |
- Germann, Matthias, et al.
(author)
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Optical frequency comb Fourier transform spectroscopy of formaldehyde in the 1250 to 1390 cm−1 range : experimental line list and improved MARVEL analysis
- 2024
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In: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 312
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Journal article (peer-reviewed)abstract
- We use optical frequency comb Fourier transform spectroscopy to record high-resolution, low-pressure, room-temperature spectra of formaldehyde (H212C16O) in the range of 1250 to 1390 cm−1. Through line-by-line fitting, we retrieve line positions and intensities of 747 rovibrational transitions: 558 from the ν6 band, 129 from the ν4 band, and 14 from the ν3 band, as well as 46 from four different hot bands. We incorporate the accurate and precise line positions (0.4 MHz median uncertainty) into the MARVEL (measured active vibration-rotation energy levels) analysis of the H2CO spectrum. This increases the number of MARVEL-predicted energy levels by 82 and of rovibrational transitions by 5382, and substantially reduces uncertainties of MARVEL-derived H2CO energy levels over a large range: from pure rotational levels below 200 cm−1 up to multiply excited vibrational levels at 6000 cm−1. This work is an important step toward filling the gaps in formaldehyde data in the HITRAN database.
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| 5. |
- Germann, Matthias, et al.
(author)
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Precision frequency comb spectroscopy in the 8 µm range
- 2023
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In: CLEO 2023. - : Optical Society of America. - 9781957171258
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Conference paper (peer-reviewed)abstract
- We use Fourier transform spectroscopy based on a compact difference frequency generation comb source emitting around 8 μm to record broadband high-resolution spectra of molecules relevant to astrophysics and environmental monitoring. From the spectra we obtain line lists with sub-MHz accuracy, an order of magnitude better than previously available, and use them to refine theoretical models of these molecules. Here we report results for formaldehyde, for which the 8 μm range is missing in HITRAN.
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| 6. |
- Rutkowski, Lucile, et al.
(author)
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An experimental water line list at 1950 K in the 6250–6670 cm−1 region
- 2018
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In: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier BV. - 0022-4073 .- 1879-1352. ; 205, s. 213-219
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Journal article (peer-reviewed)abstract
- An absorption spectrum of (H2O)-O-16 at 1950 K is recorded in a premixed methane/air flat flame using a cavity-enhanced optical frequency comb-based Fourier transform spectrometer. 2417 absorption lines are identified in the 6250-6670 cm(-1) region with an accuracy of about 0.01 cm(-1). Absolute line intensities are retrieved using temperature and concentration values obtained by tunable diode laser absorption spectroscopy. Line assignments are made using a combination of empirically known energy levels and predictions from the new POKAZATEL variational line list. 2030 of the observed lines are assigned to 2937 transitions, once blends are taken into account. 126 new energy levels of (H2O)-O-16 are identified. The assigned transitions belong to 136 bands and span rotational states up to J = 27.
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| 7. |
- Rutkowski, Lucile, et al.
(author)
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Detection of OH and H2O in an Atmospheric Flame by Near-Infrared Optical Frequency Comb Spectroscopy
- 2017
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In: 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC). - : IEEE. - 9781509067367
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Conference paper (peer-reviewed)abstract
- Absorption spectroscopy is attractive for combustion diagnostics because it allows in-situ and calibration-free quantification of reactants/products and thermometry. However, spectra measured at atmospheric pressure in the near-infrared telecom range, where laser sources and optical components are readily available, suffer from strong water interference. Cavity-enhanced optical frequency comb spectroscopy (CE-OFCS) is well suited for detection of other species, as it provides broad bandwidth with high signal-to-noise ratio and resolution, and allows de-convolving the spectra hidden among water transitions. Here we report detection of OH in the presence of H2O in an atmospheric premixed methane/air flat flame by CE-OFCS at 1.57 μm. We demonstrate a new water line list that is more accurate than HITEMP [1] and we isolate the OH lines by dividing spectra taken at different heights above the burner (HABs) to retrieve OH concentration and flame temperature.
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| 8. |
- Rutkowski, Lucile, et al.
(author)
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Experimental 1.5-1.6 μm water line list at 1950 K
- 2018
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In: Optics InfoBase Conference Papers. - : Optica Publishing Group. - 9781943580477
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Conference paper (peer-reviewed)abstract
- We demonstrate a high-temperature water absorption spectrum measured in a flame using cavity-enhanced frequency comb-based Fourier transform spectroscopy. The retrieved transition intensities and frequencies are assigned using the POKAZATEL line list.
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| 9. |
- Rutkowski, Lucile, et al.
(author)
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Measurement of H2O and OH in a Flame by Optical Frequency Comb Spectroscopy
- 2016
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In: Proceedings Conference on Lasers and Electro-Optics. - Washington, D.C. : IEEE. - 9781943580118
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Conference paper (peer-reviewed)abstract
- We measure broadband H2O and OH spectra in a flame using near-infrared cavity-enhanced Fourier transform optical frequency comb spectroscopy, we retrieve temperature and OH concentration, and compare water spectra to an improved line list.
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| 10. |
- Tinetti, G., et al.
(author)
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A chemical survey of exoplanets with ARIEL
- 2018
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In: Experimental Astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 46:1, s. 135-209
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Journal article (peer-reviewed)abstract
- Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.
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| 11. |
- Tinetti, Giovanna, et al.
(author)
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The EChO science case
- 2015
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In: Experimental astronomy. - : Springer Science and Business Media LLC. - 0922-6435 .- 1572-9508. ; 40:2-3, s. 329-391
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Journal article (peer-reviewed)abstract
- The discovery of almost two thousand exoplanets has revealed an unexpectedly diverse planet population. We see gas giants in few-day orbits, whole multi-planet systems within the orbit of Mercury, and new populations of planets with masses between that of the Earth and Neptune-all unknown in the Solar System. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? How do planetary systems work and what causes the exceptional diversity observed as compared to the Solar System? The EChO (Exoplanet Characterisation Observatory) space mission was conceived to take up the challenge to explain this diversity in terms of formation, evolution, internal structure and planet and atmospheric composition. This requires in-depth spectroscopic knowledge of the atmospheres of a large and well-defined planet sample for which precise physical, chemical and dynamical information can be obtained. In order to fulfil this ambitious scientific program, EChO was designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large, diverse and well-defined planet sample within its 4-year mission lifetime. The transit and eclipse spectroscopy method, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allows us to measure atmospheric signals from the planet at levels of at least 10(-4) relative to the star. This can only be achieved in conjunction with a carefully designed stable payload and satellite platform. It is also necessary to provide broad instantaneous wavelength coverage to detect as many molecular species as possible, to probe the thermal structure of the planetary atmospheres and to correct for the contaminating effects of the stellar photosphere. This requires wavelength coverage of at least 0.55 to 11 mu m with a goal of covering from 0.4 to 16 mu m. Only modest spectral resolving power is needed, with R similar to 300 for wavelengths less than 5 mu m and R similar to 30 for wavelengths greater than this. The transit spectroscopy technique means that no spatial resolution is required. A telescope collecting area of about 1 m(2) is sufficiently large to achieve the necessary spectro-photometric precision: for the Phase A study a 1.13 m(2) telescope, diffraction limited at 3 mu m has been adopted. Placing the satellite at L2 provides a cold and stable thermal environment as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. EChO has been conceived to achieve a single goal: exoplanet spectroscopy. The spectral coverage and signal-to-noise to be achieved by EChO, thanks to its high stability and dedicated design, would be a game changer by allowing atmospheric composition to be measured with unparalleled exactness: at least a factor 10 more precise and a factor 10 to 1000 more accurate than current observations. This would enable the detection of molecular abundances three orders of magnitude lower than currently possible and a fourfold increase from the handful of molecules detected to date. Combining these data with estimates of planetary bulk compositions from accurate measurements of their radii and masses would allow degeneracies associated with planetary interior modelling to be broken, giving unique insight into the interior structure and elemental abundances of these alien worlds. EChO would allow scientists to study exoplanets both as a population and as individuals. The mission can target super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300-3000 K) of F to M-type host stars. The EChO core science would be delivered by a three-tier survey. The EChO Chemical Census: This is a broad survey of a few-hundred exoplanets, which allows us to explore the spectroscopic and chemical diversity of the exoplanet population as a whole. The EChO Origin: This is a deep survey of a subsample of tens of exoplanets for which significantly higher signal to noise and spectral resolution spectra can be obtained to explain the origin of the exoplanet diversity (such as formation mechanisms, chemical processes, atmospheric escape). The EChO Rosetta Stones: This is an ultra-high accuracy survey targeting a subsample of select exoplanets. These will be the bright "benchmark" cases for which a large number of measurements would be taken to explore temporal variations, and to obtain two and three dimensional spatial information on the atmospheric conditions through eclipse-mapping techniques. If EChO were launched today, the exoplanets currently observed are sufficient to provide a large and diverse sample. The Chemical Census survey would consist of > 160 exoplanets with a range of planetary sizes, temperatures, orbital parameters and stellar host properties. Additionally, over the next 10 years, several new ground- and space-based transit photometric surveys and missions will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets.
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| 12. |
- Tinetti, Giovanna, et al.
(author)
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The science of EChO
- 2010
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In: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 6:S276, s. 359-370
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Journal article (peer-reviewed)abstract
- The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life. The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole. EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates. © International Astronomical Union 2011.
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| 13. |
- Zhang, Rui, et al.
(author)
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Positron collisions with molecular hydrogen: cross sections and annihilation parameters calculated using the R-matrix with pseudo-states method
- 2011
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In: J. Phys. B: At. Mol. Opt. Phys.. - 0953-4075 .- 1361-6455. ; 44:3
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Journal article (peer-reviewed)abstract
- The molecular R-matrix with pseudo-states (MRMPS) method is employed to study positron collisions with H2. The calculations employ pseudo-continuum orbital sets containing up to h (l = 5) functions. Use of these high l functions is found to give converged eigenphase sums. Below the positronium formation threshold, the calculated cross sections agree with other high-accuracy theories and generally with the measurements. Calculation of the positron annihilation parameter Zeff with the MRMPS wavefunctions gives values significantly higher than other R-matrix wavefunctions but still do not completely converge with h functions. Extrapolation to higher l-values leads to a predicted value of Zeff for H2 of about 10.4. The MRMPS method is both completely general and ab initio; it can therefore be applied to positron collisions with other molecular targets.
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