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The authors present a detailed explanation for selective reabsorption by the CO2 ν3-band when passing its optical emission through an atmospheric-pressure air column (60 cm long, 410 ppm CO2) connecting a microwave-discharge cell and the entrance window of a high-resolution Fourier Transform spectrometer. The CO2 band shapes are explained with a two-temperature model of emission and foreground absorption. Selective CO2 atmospheric reabsorption is a common effect in optical emission measurements. It primarily affects the fundamental infrared bands, which comprise the main part of the missing laboratory emission and must be taken into account in (exo)planetary atmospheric models.

Several of the Venera, Vega and Pioneer probe data as well as ground based observation support the presence of so-called Redox Disequilibrium Pairs (RDPs) in atmosphere of so hostile world as Venus (Greaves 2021). State of the art chemical networks cannot explain origin of an important RDP, phosphine, in oxidized atmosphere of Venus by a conventional processes (Bains 2021). We used the hybrid Density Functional Theory (DFT) for investigation of a series of chemical reaction pathways leading to the reduction of phosphate monoxide to phosphine. Our calculations indicated that a reaction network similar to photochemical synthesis of methane from carbon monoxide over acidic surfaces suggested for Mars (Civiš 2019) can also occur in clouds of Venus. As a seminal step, we have explored – via state-of-the-art quantum-based calculations – the a priori energetic feasibility of the following reaction:HCO(radical) + PO = CO2 + PH (biradical).Our calculations have shown that chemical conversion is constituted of three steps. Two of them are energetically favoured, however, the final conversion to phosphine is hardened by a significant activation barrier. This barrier can be overcome by a reaction of OPH radical with hydrogen radical. For assessing the potential of the newly introduced reaction mechanisms, models of the Venus and early Earth atmospheres in ARGO code and modified STAND chemical network were created and verified. Comparison of reaction yields suggests that this pathway is potentially effective enough and could be the source of phosphine recently discovered on Venus. We acknowledge the support provided by the Czech Science Foundation within the project reg. no. 21-11366S and by ERDF/ESF "Centre of Advanced Applied Sciences" (No. CZ.02.1.01/0.0/0.0/16_019/0000778). We acknowledge support of the Czech Academy of Sciences, Strategy AV21, project VP16. The Czech team is part of the VenSpec-H Consortium onboard the ESA EnVision mission.References:Civiš S. et al.: Formation of Methane and (Per)Chlorates on Mars. ACS Earth Space Chem. 2019, 3, 2, 221–232.Bains W. et al.: Phosphine on Venus Cannot Be Explained by Conventional Processes. Astrobiology 2021, 10 (21), 1277-1304.Greaves J. S. et al.: Phosphine gas in the cloud decks of Venus. Nature Astronomy 2021, 5, 655–664.

The visible spectrum of a bright Leonid bolide was recorded and analyzed by fitting the parameters of a newly developed numerical plasma model. In this procedure, elemental composition, electron density, plasma temperature, and the density of the heavy particles were extracted from the observed spectrum. The model introduced in this study involves self-absorption and takes into account the effects of the non-homogeneous meteoric plasma on the observed emission spectra using a simple radiative transfer model. The research was funded by the Czech Science Foundation (projects nos. 18-27653S, 21-11366S and 20-10591J) and partially Russian Foundation for Basic Research (grant no. 19-52-26006). Department of Spectroscopy is supported by the ERDF/ESF "Centre of Advanced Applied Sciences" project no. CZ.02.1.01/0.0/0.0/16_019/0000778.

Examination of thermal decomposition of street samples of cocaine and methamphetamine shows that typical products detected in previous studies are accompanied by a wide palette of simple volatile compounds easily detectable by spectral techniques. These molecules increase smoke toxicity and their spectral detection can be potentially used for identification of drug samples by well-controlled laboratory thermolysis in temperature progression. In our study, street samples of cocaine and methamphetamine have been thermolyzed under vacuum over the temperature range of 350–650 °C. The volatile products (CO, HCN, CH4, C2H4, etc.) have been monitored by high-resolution Fourier-transform infrared (FTIR) spectrometry in this temperature range. The decomposition mechanism has been additionally examined theoretically by quantum-chemical calculations for the highest temperature achieved experimentally in our study and beyond. Prior to analysis, the street samples have also been characterized by FTIR, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and melting point determination.

We explored the photocatalytic (UV-driven) reduction of CO2 on mineral surfaces in acidic conditions and observed the production of methane. Based on our measured laboratory reaction rates, we esti...

Spectra of meteor plasma, their dynamics and dominant spectral features are usually a subject of mathematical modelling and computations. In our study, on the other hand, we describe and evaluate the advantages and limitations of the experimental techniques employed for meteor spectra simulations. The experiments are performed by ablating meteorite samples using a series of laser sources, i.e. a large terawatt−class gas laser infrastructure PALS, a high-power Ti:Sapphire femtosecond laser, and laboratory Nd:YAG and ArF excimer lasers. We demonstrate that, notwithstanding the importance of theoretical spectra computation, laboratory experiments may remarkably enhance the qualitative and quantitative evaluation of the meteor emission spectra measured, as well as the assignment of important spectral features therein. We also perform completing experiments to compare the laser-target interaction observed with the expected dynamics of evaporation and disintegration of a real meteoroid body.

Is there life beyond Earth? An ideal research program would first ascertain how life on Earth began and then use this as a blueprint for its existence elsewhere. But the origin of life on Earth is still not understood, what then could be the way forward? Upcoming observations of terrestrial exoplanets provide a unique opportunity for answering this fundamental question through the study of other planetary systems. If we are able to see how physical and chemical environments similar to the early Earth evolve we open a window into our own Hadean eon, despite all information from this time being long lost from our planet’s geological record. A careful investigation of the chemistry expected on young exoplanets is therefore necessary, and the preparation of reference materials for spectroscopic observations is of paramount importance. In particular, the deduction of chemical markers identifying specific processes and features in exoplanetary environments, ideally “uniquely”. For instance, prebiotic feedstock molecules, in the form of aerosols and vapours, could be observed in transmission spectra in the near future whilst their surface deposits could be observed from reflectance spectra. The same detection methods also promise to identify particular intermediates of chemical and physical processes known to be prebiotically plausible. Is Ariel truly able to open a window to the past and answer questions concerning the origin of life on our planet and the universe? In this paper, we discuss aspects of prebiotic chemistry that will help in formulating future observational and data interpretation strategies for the Ariel mission. This paper is intended to open a discussion and motivate future detailed laboratory studies of prebiotic processes on young exoplanets and their chemical signatures.

The photocatalytic reduction of CO2 to CH4 is a chemical process that to some extent occurs on a planetary surface of terrestrial planets. The effect of acidic proton on the rate of the photocataly...

Ariel, the Atmospheric Remote-sensing Infrared Exoplanet Large-survey, was adopted as the fourth medium-class mission in ESA's Cosmic Vision programme to be launched in 2029. During its 4-year mission, Ariel will study what exoplanets are made of, how they formed and how they evolve, by surveying a diverse sample of about 1000 extrasolar planets, simultaneously in visible and infrared wavelengths. It is the first mission dedicated to measuring the chemical composition and thermal structures of hundreds of transiting exoplanets, enabling planetary science far beyond the boundaries of the Solar System. The payload consists of an off-axis Cassegrain telescope (primary mirror 1100 mm x 730 mm ellipse) and two separate instruments (FGS and AIRS) covering simultaneously 0.5-7.8 micron spectral range. The satellite is best placed into an L2 orbit to maximise the thermal stability and the field of regard. The payload module is passively cooled via a series of V-Groove radiators; the detectors for the AIRS are the only items that require active cooling via an active Ne JT cooler. The Ariel payload is developed by a consortium of more than 50 institutes from 16 ESA countries, which include the UK, France, Italy, Belgium, Poland, Spain, Austria, Denmark, Ireland, Portugal, Czech Republic, Hungary, the Netherlands, Sweden, Norway, Estonia, and a NASA contribution., Comment: Ariel Definition Study Report, 147 pages. Reviewed by ESA Science Advisory Structure in November 2020. Original document available at: https://www.cosmos.esa.int/documents/1783156/3267291/Ariel_RedBook_Nov2020.pdf/

In this work we present a time-resolved FTIR spectroscopic study on kinetics of atomic and molecular species, specifically CO, CN radical, N

Two sets of NH3 absorption spectra covering the 0.793 μm region are recorded using two Bruker IFS 125 HR Fourier transform spectrometers. Three unapodized absorption spectra are recorded in Brussels over the range 11000−14500 cm−1 and the positions and intensities of 1114 ammonia lines observed in the 12491−12810 cm−1 region are measured using a multi-spectrum least squares fitting algorithm. 367 additional lines are identified in an ammonia absorption spectrum recorded in two steps at the J. Heyrovsky Institute of Physical Chemistry in Prague, using two different interference filters covering the 12000−12500 and 12400−13000 cm−1 ranges. The 1481 measured ammonia lines are analyzed using an empirical line list computed using variational nuclear motion calculations and ground state combination differences. Transitions are assigned to vibrational states with 4νNH stretching excitation (v1+v3=4). 278 out of the 1481 measured lines are assigned to 300 transitions and 119 upper state energy levels are derived from the frequencies of the assigned transitions., SCOPUS: ar.j, info:eu-repo/semantics/published

Besides delivering plausible prebiotic feedstock molecules and high-energy initiators, extraterrestrial impacts could also affect the process of abiogenesis by altering the early Earth's geological environment in which primitive life was conceived. We show that iron-rich smectites formed by reprocessing of basalts due to the residual post-impact heat could catalyze the synthesis and accumulation of important prebiotic building blocks such as nucleobases, amino acids and urea.

Methane, perchlorates, chlorates, and methyl chlorides have all been detected on Mars. The origin of these species has never been adequately explained. In this paper, we irradiated mixtures of CO2,...

Synthesis of RNA nucleobases from formamide is one of the recurring topics of prebiotic chemistry research. Earlier reports suggest that thymine, the substitute for uracil in DNA, may also be synthesized from formamide in the presence of catalysts enabling conversion of formamide to formaldehyde. In the current paper, we show that to a lesser extent conversion of uracil to thymine may occur even in the absence of catalysts. This is enabled by the presence of formic acid in the reaction mixture that forms as the hydrolysis product of formamide. Under the reaction conditions of our study, the disproportionation of formic acid may produce formaldehyde that hydroxymethylates uracil in the first step of the conversion process. The experiments are supplemented by quantum chemical modeling of the reaction pathway, supporting the plausibility of the mechanism suggested by Saladino and coworkers.

In a combined experimental and theoretical study, we probe the vibrational excitation of isocyanic acid induced by electron impact in the energy range up to 5 eV. Experimentally, we report differential elastic and vibrationally inelastic cross sections at the scattering angle of ${135}^{\ensuremath{\circ}}$. Theoretically, we characterize the involved resonant states using a regularized analytical continuation method. We also apply a nonlocal resonance model to calculate cross sections for vibrational mode that involves the N-H stretching motion. The model reproduces all the features observed in the experiment: efficient excitation at threshold, sharp cusps in the excitation functions, and the formation of an ${A}^{\ensuremath{'}}$ shape resonance. There is a second $({A}^{\ensuremath{'}\ensuremath{'}})$ resonance visible in the spectra; however, it excites only selected vibrational modes. The origins of this selectivity are discussed.

Although the effect of ionizing radiation on prebiotic chemistry is often overlooked, primordial natural radioactivity might have been an important source of energy for various chemical transformations. Estimates of the abundances of short-lived radionuclides on early Earth suggest that the primordial intensity of endogenous terrestrial radioactivity was up to 4 × 103 times higher than it is today. Therefore, we assume that chemical substances in contact with radioactive rocks should therefore undergo radiolysis. The calculations are followed by research investigating the influence of ionizing γ radiation on basic prebiotic substances, including formamide mixed with various clays, which might have played the role of a catalyst and an agent that partially blocked radiation that was potentially destructive for the products. Our explorations of this effect have shown that the irradiation of formamide-clay mixtures at doses of ∼6 kGy produces significant amounts of urea (up to the maximal concentration of approximately 250 mg L-1), which plays a role in HCN-based prebiotic chemistry.

Terrestrial volcanism has been one of the dominant geological forces shaping our planet since its earliest existence. Its associated phenomena, like atmospheric lightning and hydrothermal activity, provide a rich energy reservoir for chemical syntheses. Based on our laboratory simulations, we propose that on the early Earth volcanic activity inevitably led to a remarkable production of formic acid through various independent reaction channels. Large-scale availability of atmospheric formic acid supports the idea of the high-temperature accumulation of formamide in this primordial environment.

All the spectra presented in this atlas were measured with the time-resolved Fourier-transform infrared (FTIR) spectrometer at the Department of Spectroscopy, J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences. The original purpose in constructing time-resolved hardware was to directly observe the excitation and de-excitation of atomic and molecular species as well as follow chemical processes in periodically-excited systems.

The chemical environments of young planets are assumed to be largely influenced by impacts of bodies lingering on unstable trajectories after the dissolution of the protoplanetary disk. We explore the chemical consequences of impacts within the context of reducing planetary atmospheres dominated by carbon monoxide, methane and molecular nitrogen. A terawatt high-power laser was selected in order to simulate the airglow plasma and blast wave surrounding the impactor. The chemical results of these experiments are then applied to a theoretical atmospheric model. The impact simulation results in substantial volume mixing ratios within the reactor of 5% hydrogen cyanide (HCN), 8% acetylene (C$_2$H$_2$), 5% cyanoacetylene (HC$_3$N) and 1% ammonia (NH$_3$). These yields are combined with estimated impact rates for the Early Earth to predict surface boundary conditions for an atmospheric model. We show that impacts might have served as sources of energy that would have led to steady-state surface quantities of 0.4% C$_2$H$_2$, 400 ppm HCN and 40 ppm NH$_3$. We provide simulated transit spectra for an Earth-like exoplanet with this reducing atmosphere during and shortly after eras of intense impacts. We predict that acetylene is as observable as other molecular features on exoplanets with reducing atmospheres that have recently gone through their own `Heavy Bombardments', with prominent features at 3.05 $\mu$m and 10.5 $\mu$m., Comment: 26 pages, 12 figures, 2 tables, accepted for publication by The Astrophysical Journal

The era of fossil fuels is slowly nearing its inevitable end and the urgency of alternative energy sources basic research, exploration and testing becomes ever more important. Storage and alternative production of energy from fuels, such as methane, represents one of the many alternative approaches. Natural gas containing methane represents a powerful source of energy producing large volume of greenhouse gases. However, methane can be also produced in closed, CO2-neutral cycles. In our study, we compare detailed chemical composition of CH4 fuel produced in two different processes: Classical production of biogas in a rendering station, industrial wastewater treatment station and landfill gas station together with novel approach of artificial photosynthesis from CO2 over acidic anatase TiO2 in experimental apparatus developed in our laboratory. The analysis of CH4 fuel produced in these processes is important. Trace gaseous traces can be for example corrosive or toxic, low quality of the mixture suppresses effectivity of energy production, etc. In this analysis, we present a combination of two methods: High resolution Fourier transform infrared spectroscopy (HR-FTIR) suitable for the main component analysis; and the complementary extremely sensitive method of Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) and gas chromatography (GC–MS), which are in turn best suited for trace analysis. The combination of these methods provides more information than any single of them would be able to and promises a new possible analytical approach to fuel and gaseous mixture analysis.

The intensity ratio of the D 1 and D 2 sodium-doublet emission lines varies both across spectra of astronomical sources and in laboratory plasmala. This article probes the behaviour of this ratio under controlled laboratory conditions. In order to study this variation, we have recorded microwave discharge spectra of sodium vapour in range of 15000 to 18000 cm − 1 . Emission bands of the molecular nitrogen buffer gas and kinetic broadening of nitrogen and sodium lines have been used in a characterisation of the discharge temperature. We show that the relative intensity of doublet lines is determined by self-absorption and depends on the buffer-gas pressure and discharge power. The ratio and line shapes can be explained by a two-temperature model of sodium emission and foreground absorption. Line ratios estimated for spectra with various strength of the self-absorption of electric discharges can be used for characterising their temperatures and densities. In contemporary astronomical observation of exoplanetary atmospheres, this effect has not been resolved yet. To observe this effect, at least 0.01 - 0.05 cm − 1 resolution (resolving power 1 600 000) is required. We make a connection to stellar Na emission and possible absorption processes for future observations of exoplanetary atmospheres.

Capillary electromigration techniques have proven their capabilities in detection of variety of analytes from inorganic ions and small organic molecules through bio(macro)molecules to large analytes such as cells or nano/micro particles. Also broad range of potential applications includes food and environmental analysis, biomedical and pharmaceutical investigations or even diagnostics. In this work, it was demonstrated that capillary micellar electrokinetic chromatography is an excellent tool extremely helpful in investigations focused on prebiotic synthesis of molecules essential for formation of life on early Earth – nucleobases. In particular, rapid separation of nucleobases (

Endohedral fullerenes with paramagnetic encapsulated atoms are new magnetic materials of interest for numerous applications from medicine to quantum computers. An important phenomenon with endohedral fullerenes is the appearance of new vibrational frequencies not associated with empty fullerenes. The vibrational spectra of the lanthanide endohedral fullerenes La@C60 and Ce@C60 in various spin states are calculated using the density functional method. Most of the spectral lines lie in the 300–1600 cm - 1 range, and their intensities change dramatically depending on the molecule’s symmetry and spin state, which are determined by the encapsulated lanthanide atom. The average frequency shift of the carbon cage vibrations caused by spin transition is only 5 cm - 1 . The calculated frequencies of the coupled “metal–carbon cage” vibrations of the lanthanide endohedral fullerenes La@C60 and Ce@C60 in various spin states lie in the 10–170 cm - 1 range. The computational results for both the frequencies and intensities of the metal–cage modes depend considerably on the spin state. The changes in these vibrational modes are due to the changes in the molecular symmetry and the metal–carbon bond lengths. Such dependence can be used as a basis for controlling the spin state of metallofullerenes by measuring the vibration frequencies in the far-infrared zone, which could be important for nanoelectronics and quantum informatics.

Understanding the chemical evolution of newly formed terrestrial planets involves uncertainties in atmospheric chemical composition and assessing the plausibility of biomolecule synthesis. In this study, an original scenario for the origin of methane on Mars and terrestrial planets is suggested. Carbon dioxide in Martian and other planetary atmospheres can be abiotically converted into a mixture of methane and carbon monoxide by ‘methanogenesis’ on porous mineral photoactive surfaces under soft ultraviolet irradiation. On young planets exposed to heavy bombardment by interplanetary matter, this process can be followed by biomolecule synthesis through the reprocessing of reactive reducing atmospheres by impact-induced shock waves. The proposed mechanism of methanogenesis may help to answer the question concerning the formation of methane and carbon monoxide by photochemical processes, the formation of biomolecules on early Earth and other terrestrial planets, and the source and seasonal variation of methane concentrations on Mars. Experiments are presented that indicate that methane can be produced abiotically on Mars through the photocatalytic reaction of CO2, in a process called methanogenesis. Methane can then be shocked (through impacts) to form RNA nucleobases and glycine.

Recent results in prebiotic chemistry implicate hydrogen cyanide (HCN) as the source of carbon and nitrogen for the synthesis of nucleotide, amino acid and lipid building blocks. HCN can be produced during impact events by reprocessing of carbonaceous and nitrogenous materials from both the impactor and the atmosphere; it can also be produced from these materials by electrical discharge. Here we investigate the effect of high energy events on a range of starting mixtures representative of various atmosphere-impactor volatile combinations. Using continuously scanning time–resolved spectrometry, we have detected ·CN radical and excited CO as the initially most abundant products. Cyano radicals and excited carbon monoxide molecules in particular are reactive, energy-rich species, but are resilient owing to favourable Franck–Condon factors. The subsequent reactions of these first formed excited species lead to the production of ground-state prebiotic building blocks, principally HCN.

The mechanical behaviours of multilayer graphene (MLG) membranes and cantilevers were investigated for the sensitive detection of acoustic waves in gases. The aim of this work was to find sensors for laser photoacoustic spectroscopy with high sensitivity. The application of the MLG cantilever for photoacoustic detection was reported for the first time. MLG membranes and cantilevers were prepared from highly ordered pyrolytic graphite (HOPG) by multiple mechanical cleavages allowing simple adjustment of the membrane/cantilever thickness and relevant mechanical parameters. The MLG cantilever/membrane movements induced by pressure waves triggered by the absorption of the CO 2 laser pulse in the gas-filled photoacoustic cell were detected by a He-Ne laser beam reflected from the cantilever/membrane to a position sensitive detector (optical microphone). The sensitivity of the MLG cantilevers for the photoacoustic detection of methanol vapours (testing gas) was more than one order of magnitude higher in comparison with a top class microphone (Bruel & Kjaer). The signal-to-noise ratio of 19, 61, and 70 together with the limits of detection of 0.75 ppm, 0.42 and 0.33 ppm were calculated for the condenser microphone, the MLG membrane, and the MLG cantilever, respectively. Additionally, the high sensitivity of both MLG elements for the photoacoustic detection is also promising thanks to the single layer graphene with very a small thickness on the nanometer scale.

In a series of our previously published papers, we reported a broad range of experiments and theoretical studies devoted to the interaction of carbon dioxide with the anatase titania surface. In the current study, we demonstrate oxygen mobility between gaseous carbon dioxide and solid natural clay minerals. This surprising feature implies that such behaviour is typical not only for titania but also for oxides with different chemical composition and structure. The oxygen mobility was demonstrated by the interaction of isotopically labelled carbon dioxide – C 18 O 2 – with the mineral surfaces. In most cases, we observed rapid oxygen exchange between the gas and the mineral. It was therefore discovered that carbon dioxide is more active than was previously thought because it exchanges its oxygen atoms with inorganic surfaces. Moreover, this feature seems to be very significant in natural clays of various compositions. This finding points not only towards high activity of CO 2 but also towards high surface reactivity of clays, which are quite common surface minerals on Earth and other planets.

Atomic argon spectrum in the range of 1200–2000 cm–1 has been recorded by time-resolved Fourier transform spectroscopy. The lines have been identified using the oscillator strengths calculated by the quantum-defect method. Previously unknown energies of the 6h levels of Ar I have been found from the spectrum.

The origin of methane on Mars and other terrestrial planets in their early or late stages of chemical evolution has never been explained in a satisfactory way. Here we propose a photochemistry-based scenario of carbon dioxide reduction to methane on semiconductor photocatalysts, such as TiO 2 . This approach takes inspiration in the same reaction chain used in environmental chemistry research since the late 1970s. On Mars, this scenario could unveil the origin of methane, which has been hotly debated recently. On young extra-terrestrial planets, this process could supply the atmosphere with reduced gases and facilitate organic synthesis and possibly the origin of life in these new born worlds.

One of the exceptional features of CO2 is its ability to interact with solid surfaces on a common basis. This interaction takes the form of an adsorption and can be monitored by isotope labelling. Oxygen isotope-labelled CO2 added to a mineral, most importantly TiO2, exchanges its oxygen atoms with the sample and the changing isotopic composition can be monitored by high-resolution Fourier transform infrared spectroscopy.

Last a few decades have witnessed a rising scientific interest in two well-known molecules—carbon dioxide and titania. The fundamental properties such as their chemistry, structure and application potential are well known. However, the main problem concerning CO2—the global change of climate—has not been dealt with yet. The ever-rising levels of carbon dioxide in the atmosphere, utilization of fossil fuels and the effects on global climate portend the need for a cleaner energy supply as well as the need to reduce the CO2 amount present in the atmosphere of our planet. Importantly, several recent discoveries have pointed out that novel materials based on TiO2 are able to solve climate change by establishing a new methane cycle-based energetics and economy.

The field of the origin of life research is a relatively new but rapidly growing area of research. It is not the purpose of this book to review all scientific progress in this branch. Indeed, such book would have to be quite thicker, not to mention expensive. However, several ideas that have recently come up concerning the early Earth and life’s origins include CO2 and/or TiO2 as the main protagonists. We wish to mention to a certain extent these ideas and show that photochemistry might have played a vital role in the process by which we came to being.

This chapter gives an overview of the state-of-the-art research progress in the topic of photocatalytic reduction of CO2 in selected areas of application. The knowledge of the practical uses of the photocatalytic reduction process may be beneficial to give the book more context and to specify its place in the plethora of work that is available to any reader.

The photocatalytic reduction of carbon dioxide is a process that has received significant attention in the literature of the second half of the twentieth century. This chapter shows how chemical conditions and the environment can envisage various aspects of this process and explains what consequences these findings may have on the origin of methane on terrestrial planets, which is shown on the case of Mars.