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The increasing use of high-sulfur coal contradicts with the stringent environmental pressure in metallurgical industry. Microwave has been confirmed to have efficient effect for coal desulfurization. However, the removal behavior of thiophenic sulfur, as the most difficult sulfur to remove from coal, is still unclear in microwave field. In this work, the feasibility of removing thiophenic sulfur from coal by microwave was evaluated by dielectric properties test, the chemical thermodynamics and kinetics of thiophenic sulfur migration with microwave irradiation were further analyzed by density functional theory (DFT) calculation. Dielectric properties test indicates that thiophenic sulfur is strong for converting electric field energy to heat energy than coal, which means the thiophenic sulfur will be selectively heated in the process of coal desulfurization by microwave. The magnetic loss powers of coal and thiophenic sulfur are very small and can be ignored. DFT calculation shows that under microwave irradiation, the energy barrier and activation energy of rate-limiting step for thiophenic sulfur removal decrease by 7.6 kJ/mol and 2.24 kcal/mol, and the logarithm of rate constant increases by 11.2 s−1. It suggests that the thiophenic sulfur removal is promoted by catalyzing the breaking of C–H and C–C bonds. In addition, the optimal removal path of thiophenic sulfur is also changed, accompanying the variation of sulfur-containing products from carbon monosulfide (CS) to thioketene (C2H2S). These findings reveal the catalytic mechanism of microwave on the thiophenic sulfur removal from coal, which are conducive to the sustainable utilization of high-sulfur coal in metallurgy process.

We report the first survey of molecular emission from cometary volatiles using standalone Atacama Compact Array (ACA) observations of the Atacama Large Millimeter/Submillimeter Array (ALMA) toward comet C/2015 ER61 (PanSTARRS) carried out on UT 2017 April 11 and 15, shortly after its April 4 outburst. These measurements of HCN, CS, CH$_3$OH, H$_2$CO, and HNC (along with continuum emission from dust) probed the inner coma of C/2015 ER61, revealing asymmetric outgassing and discerning parent from daughter/distributed source species. This work presents spectrally integrated flux maps, autocorrelation spectra, production rates, and parent scale lengths for each molecule, and a stringent upper limit for CO. HCN is consistent with direct nucleus release in C/2015 ER61, whereas CS, H$_2$CO, HNC, and potentially CH$_3$OH are associated with distributed sources in the coma. Adopting a Haser model, parent scale lengths determined for H$_2$CO (L$_p$ $\sim$ 2200 km) and HNC (L$_p$ $\sim$ 3300 km) are consistent with previous work in comets, whereas significant extended source production (L$_p$ $\sim$ 2000 km) is indicated for CS, suggesting production from an unknown parent in the coma. The continuum presents a point-source distribution, with a flux density implying an excessively large nucleus, inconsistent with other estimates of the nucleus size. It is best explained by the thermal emission of slowly-moving outburst ejectas, with total mass 5--8 $\times$ 10$^{10}$ kg. These results demonstrate the power of the ACA for revealing the abundances, spatial distributions, and locations of molecular production for volatiles in moderately bright comets such as C/2015 ER61.

Artículo escrito por un elevado número de autores, solo se referencia el que aparece en primer lugar, el nombre del grupo de colaboración, si lo hubiere, y los autores pertenecientes a la UAM, Context. Carbon monosulphide (CS) is among the most abundant gas-phase S-bearing molecules in cold dark molecular clouds. It is easily observable with several transitions in the millimeter wavelength range, and has been widely used as a tracer of the gas density in the interstellar medium in our Galaxy and external galaxies. However, chemical models fail to account for the observed CS abundances when assuming the cosmic value for the elemental abundance of sulfur. Aims. The CS+O → CO + S reaction has been proposed as a relevant CS destruction mechanism at low temperatures, and could explain the discrepancy between models and observations. Its reaction rate has been experimentally measured at temperatures of 150-400 K, but the extrapolation to lower temperatures is doubtful. Our goal is to calculate the CS+O reaction rate at temperatures, The research leading to these results has received funding from MICIU (Spain) under grants FIS2017-83473-C2, AYA2016-75066- C2-2-P, ESP2017-86582-C4-1-R, AYA2017-85111-P, PID2019-105552RB-C41 and PID2019-106235GB-I00. N.B. acknowledges the computing facilities by TUBITAK-TRUBA, and O.R. and A.A. acknowledge computing time at Finisterre (CESGA) and Marenostrum (BSC) under RES computational grants ACCT-2019-3-0004 and AECT-2020-1-0003. SPTM acknowledges the European Union’s Horizon 2020 research and innovation program for funding support under agreement No 639459 (PROMISE)

An indirect method for the determination of cysteine in pharmaceutical formulations involving the monitoring of CS (carbon monosulfide) molecular absorption bands using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) is reported. The best conditions for the determination were based on the sum of the absorbance signals of the molecular transition lines for CS at 258.034 and 258.056 nm with a pyrolysis temperature of 1000 °C and a volatilization temperature of 2400 °C using Pd/Mg as a chemical modifier. The linear range for cysteine was 1.4 to 100 mg kg−1 with a limit of detection and limit of quantification of 0.4 and 1.3 mg kg−1, respectively. The precision, evaluated as relative standard deviation (RSD), was 3.7% (n = 10) for a sample containing 25.0 mg kg−1 of cysteine. The accuracy of sulfur determination was evaluated using a standard reference material (NIST-SRM-1573a tomato leaves) and concordant values were observed within the 95% confidence interval. The method was successfully applied to the analysis of pharmaceutical formulation samples containing cysteine, lysine, and alanine. The concentrations of cysteine found in the samples were between 9.8 and 20.1 mg kg−1.

WOS: 000440769400013 PubMed ID: 29998966 The determination of sulfur in apricot and grape samples was performed by using high-resolution continuum source electrothermal molecular absorption spectrometry based on vaporization of the carbon monosulfide (CS) molecule. CS forms in the gas phase without the addition of any molecule-forming element, since graphite cuvette contains plenty of carbon as well as food samples. A mixture of 15 mu g Pd + 10 mu g Mg was used in solution as the chemical modifier. The best sensitivity was obtained at 900 degrees C of the pyrolysis temperature with a K2SO4 calibration solution. The calibration plot drew a linear path between 50 and 1600 ng of sulfur, and the limit of detection was found to be 23 ng. The accuracy of the method was confirmed with the use of a standard reference material (Rice Flour, NIST SRM 1568a). The sulfur content in chemically dried apricot samples (1987 +/- 45 mg/kg) was determined to be higher than that of apricot samples dried under sunshine. Council of Higher Education of TurkeyMinistry of National Education - Turkey [2547/39] The authors wish to thank financial support of the foundation of The Council of Higher Education of Turkey (No. 2547/39). This study was funded by No. 2547/39

The feasibility of direct laser cooling of SiH, GeH, SnH, and PbH is investigated and assessed based upon first principles. The internally contracted multi-reference configuration interaction method with the Davidson correction is applied. Very good agreement is obtained between our computed spectroscopic constants and the available experimental data. We find that the locations of crossing point between the B2Σ- and A2Δ states have the tendency of moving downwards from CH to SnH relative to the bottom of the corresponding A2Δ potential, which precludes the laser cooling of GeH, SnH, and PbH. By including the spin-orbit coupling effects and on the basis of the A 2 Δ 5 / 2 → X 2 Π 3 / 2 transition, we propose a feasible laser cooling scheme for SiH using three lasers with wavelengths varying from 400 to 500 nm, which features a very large vibrational branching ratio (0.9954) and a very short radiative lifetime (575 ns). Moreover, similar studies are extended to carbon monosulfide (CS) with a feasible laser cooling scheme proposed. The importance of electronic state crossing in molecular laser cooling is underscored, and our work suggests useful caveats to the choice of promising candidates for producing ultracold molecules.

Carbon monosulfide was detected in outer space by rovibrational spectroscopy of the X 1Σ+ state and A 1Π – X 1Σ+ system. This work calculated the potential energy curves and dipole moment functions of the X 1Σ+0+ and A 1Π1 states, and computed the transition dipole moments between the two states employing the CASSCF method, followed by the valence icMRCI approach. Core-valence correlation and scalar relativistic corrections were included. The extrapolation of potential energies to the complete basis set limit was performed. The spin-orbit coupling effect was included. The Einstein A coefficients, band origins, and oscillator strengths were calculated for the rovibrational transitions when J ≤ 150. The rovibrational transitions of the X 1Σ+0+ and A 1Π1 states became very weak when Δυ ≥ 6. The Einstein A coefficients of vibronic emissions of the A 1Π1 – X 1Σ+0+ system were large, indicating that the emissions were able to be measured easily through spectroscopy. Several rovibrational transitions of the A 1Π1 – X 1Σ+0+ system were analysed in detail. The distribution of radiative lifetime varying as rotational quantum number was calculated. The results obtained in this work agree well with the available experimental values.

The 29 reactions linking carbon monosulfide (CS) to methyl mercaptan (CH3SH) via ten intermediate radicals and molecules have been characterized with relevance to surface chemistry in cold interstellar ices. More intermediate species than previously considered are found likely to be present in these ices, such as trans- and cis-HCSH. Both activation and reaction energies have been calculated, along with low-temperature (T > 45~K) rate constants for the radical-neutral reactions. For barrierless radical-radical reactions on the other hand, branching ratios have been determined. The combination of these two sets of information provides, for the first time, quantitative information on the full H + CS reaction network. Early on in this network, that is, early on in the lifetime of an interstellar cloud, HCS is the main radical, while later on this becomes first CH2SH and finally CH3S., Accepted for publication in A&A Lett

Herein we show using theoretical predictions that carbon monosulfide compounds exhibit a variety of layered nanostructures, such as chain arrays, monolayers, and thin films. We show that semiconductor chain arrays are the most stable because they are mainly dimensionality driven by sp2 hybridization of the carbon orbitals. In contrast to the thin films, the monolayers are stable at room temperature in a semiconductor phase, which is followed in energy by a metallic phase. Moreover, we study a semiconductor-to-metal phase transition in the carbon monosulfide monolayers by strain engineering to control the conductivity and carrier mobility., This work was partially supported by Projects FIS2013-48286-C02-01-P and FIS2016-76617-P of the Spanish Ministry of Economy and Competitiveness MINECO, the Basque Government under the ELKARTEK project (SUPER), and the University of the Basque Country (Grant No. IT-756-13).

A coherent picture is constructed on the Galaxy's H I, CO and CS emissions in the region |l| ≤ 10°, |b| ≤ 0.5°. The flow of gas at the Galactic Centre is dominated by a bar that has corotation at r = 2.4 ± 0.5 kpc, which we view at an angle of 16 ± 2° from its major axis. The first CO emission arises where gas is obliged to switch from x 1 orbits to x 2 orbits in the notation of Contopoulos. This gives rise to a shock and a clear signature in the (l, v) diagram. The great Galactic Centre molecular clouds such as Sgr B are on x 2 orbits.

A new series of compounds with a sulfur-carbon triple bond-SCX(2+), SCXF(+), and SCXF2 (X = Be, Mg, Ca)-were investigated using quantum chemical computations. The B3LYP, M06-2X, MP2, CCSD, and G4 methods were employed to predict the structures, harmonic vibrational frequencies, Wiberg bond indices, and adiabatic bond dissociation energies (ABDEs) for these compounds. When calculated at the B3LYP/cc-pVTZ level, the S≡C bonds were found to be rather short: 1.4855-1.4984, 1.4893-1.5078, and 1.5123-1.5184 Å for the doubly charged cations, singly charged cations, and neutral molecules, respectively. Interestingly, they are much shorter than in the strong sulfur-carbon triple bond in carbon monosulfide (1.5371 Å). Moreover, NBO analysis together with the results for the structures and Wiberg bond indices indicated that the S≡C bonds in SCX(2+), SCXF(+), and SCXF2 (X = Be, Mg, Ca) should be strong triple bonds. Further, the ABDE values of S≡C in SCX(2+) (209.8-250.6 kcal/mol) and SCXF(+) (174.6-217.6 kcal/mol), but not SCXF2 (150.5-174.4 kcal/mol), are larger than that of S≡C in carbon monosulfide (170.7 kcal/mol); however, upon comparing them with previously published data on other compounds with sulfur-carbon triple bonds, the S≡C bonds in SCXF2 molecules appear to be much stronger than those S≡C triple bonds. In general, all of the results calculated in this work clearly indicate that the SCX(2+), SCXF(+), and SCXF2 (X = Be, Mg, Ca) species each contain a strong sulfur-carbon triple bond.

The construction of a millimeterwave spectrometer to study the pure rotational spectra of transient molecules in the gas phase is presented. The spectrometer is a source-modulated system combined with a free space glass discharge cell. Millimeterwave radiation has been produced using a frequency multiplier, the fundamental radiation source being klystrons. The spectrometer has been used to study the millimeterwave spectrum of carbon monosulfide (CS) and fluorine cyanide (FCN) produced inside the cell in a low pressure DC discharge of precursor gases. The quadrupole hyperfine structures of33S and14N nucleus of CS and FCN have been resolved, measured and analysed.

Highly correlated calculations are performed on the primary ionic states and the prominent satellite present in the outer valence photoelectron spectrum of carbon monosulfide (CS). Dyson orbitals are coupled to accurate one particle continuum orbitals to provide a correlated description of energy dependent cross sections, asymmetry parameters, branching ratios, and molecular frame photoelectron angular distributions. The comparison with results obtained at the Hartree-Fock and Density Functional Theory level shows the strong sensitivity of these observables to details of the correlation in the bound states. The behaviour of the well characterized satellite state is analyzed in detail, and shows differences from the relevant primary states, revealing the limitations of a simple intensity borrowing mechanism. The results resolve the intensity disagreement with experiment obtained at the level of the sudden approximation.

Carbon monosulfide (CS), which plays an important role in a variety of research fields, has long received considerable interest. Due to its transient nature and large state density, the electronic states of CS have not been well understood, especially the interactions between different states. In this paper, we performed a detail ab initio study on the low-lying electronic states of CS by means of the internally contracted multireference configuration interaction method (including Davidson correction) with scalar relativistic correction using the Douglas-Kroll-Hess Hamiltonian. We focused on the spin-orbit coupling of the states via the state interaction method with the full Breit-Pauli Hamiltonian. The potential energy curves (PECs) of 18 Λ-S states correlated with the lowest dissociation limit of the CS molecule were calculated, as well as those of 50 Ω states generated from the Λ-S states. The spectroscopic constants of the bound states were obtained, which are in good agreement with previous available experimental and theoretical results. The state perturbations of the a(3)Π and A(1)Π states with other low-lying electronic states are discussed in detail, based on the calculated spin-orbit matrix as well as the PECs of the Ω states. Avoided crossing in the states of CS was indicated when spin-orbit coupling was taken into account. Finally, the allowed transition dipole moments as well as the lifetimes of the five lowest vibrational states of the A(1)Π1, A'(1)Σ(+)0(+) and a(3)Πi states were obtained.

Texto completo: acesso restrito. p. 368–374 Submitted by Edileide Reis (leyde-landy@hotmail.com) on 2014-12-17T12:36:14Z No. of bitstreams: 1 Renata Mior.pdf: 601957 bytes, checksum: 1dec8ac65854df78eaa59c1ea468ec75 (MD5) Made available in DSpace on 2014-12-17T12:36:14Z (GMT). No. of bitstreams: 1 Renata Mior.pdf: 601957 bytes, checksum: 1dec8ac65854df78eaa59c1ea468ec75 (MD5) Previous issue date: 2013 An analytical method has been developed for the determination of sulfur in coal using direct solid sample analysis in a graphite tube furnace and high-resolution continuum source molecular absorption spectrometry (HR-CS GF MAS). The molecular absorbance of the carbon monosulfide molecule (CS), which is formed in the vaporization stage, has been measured using the rotational line at 258.033 nm. Several chemical modifiers were tested and Ru, applied as permanent modifier was chosen, because it exhibited the best performance. The optimum pyrolysis and vaporization temperatures were found to be 500 °C and 2200 °C, respectively. Aqueous standard solutions prepared from l-cysteine were used for calibration, as the linear regression obtained for this standard was not significantly different from that for a certified coal reference material (CRM) according to a Student t-test. The results obtained for sulfur in three coal CRM and six additional samples also showed no significant difference for the two calibration techniques according to the same statistical test. The sulfur concentration in the coal samples was found between 3.5 mg g−1 and 33.7 mg g−1 with a typical repeatability around 10%. The limit of detection for the direct analysis of solid coal samples was better than 0.1 μg S.

In Jupiter's stratosphere, gaseous carbon monosulfide (CS) was first discovered in 1994 by millimeter and ultraviolet observations as a product induced by the collision of comet Shoemaker–Levy 9 (SL9). To constrain sulfur chemistry, in 2013, 19 years after the SL9 event, we observed Jupiter's stratospheric CS J = 7 − 6 rotational transition at 0.8 mm wavelength by using the Atacama Submillimeter Telescope Experiment 10 m single-dish telescope. The CS molecular line was successfully detected with 120 mK intensity in the antenna temperature scale. The obtained CS total mass shows ~90% decrease relative to that observed in 1998. From the line shape analysis, CS is suggested to be present above the mbar pressure level, which is comparable to that determined in 1998.

An analytical method has been developed for the determination of sulfur in coal using direct solid sample analysis in a graphite tube furnace and high-resolution continuum source molecular absorption spectrometry (HR-CS GF MAS). The molecular absorbance of the carbon monosulfide molecule (CS), which is formed in the vaporization stage, has been measured using the rotational line at 258.033 nm. Several chemical modifiers were tested and Ru, applied as permanent modifier was chosen, because it exhibited the best performance. The optimum pyrolysis and vaporization temperatures were found to be 500 °C and 2200 °C, respectively. Aqueous standard solutions prepared from l-cysteine were used for calibration, as the linear regression obtained for this standard was not significantly different from that for a certified coal reference material (CRM) according to a Student t-test. The results obtained for sulfur in three coal CRM and six additional samples also showed no significant difference for the two calibration techniques according to the same statistical test. The sulfur concentration in the coal samples was found between 3.5 mg g(-1) and 33.7 mg g(-1) with a typical repeatability around 10%. The limit of detection for the direct analysis of solid coal samples was better than 0.1 μg S.

We have mapped the young star formation region DR21(OH) in the J=2-1 and 1-0 transitions of CS and C 34 S, and have obtained spectra with high signal-to-noise ratios towards the three main continuum sources within the core. We find that the CS emission corresponds closely with the thermal continuum, and that all three continuum sources are well separated in velocity as well as spatially. We suggest that wing emission in the CS lines is associated with an outflow originating from DR21(OH)Main, which also excites the observed CH 3 OH masers. Our CS line profiles show clear self-absorption redshifted by about 0.5 km s −1 relative to the rest velocity of the cloud. In order to account for this feature, we also suggest that there is residual contraction of the outer, less dense, parts of the cloud

A 7-arcmin strip along the OMC1 ridge has been mapped in the transitions 13 CO J = 2-1, 13 CS J = 5-4 and CN N = 2-1. The cyanogen radical is found not to have an exceptionally high abundance in the so-called 'Radical Region'. Strong CN N = 1-0 emission detected previously instead results from a low excitation temperature. The N = 2-1 transition is subthermalized, in spite of optical depths as high as 3, and this is explained in terms of non-LTE effects. The chemistry of the Radical Region is examined using results from a recent spectral survey. The abundances of HCN, CS, C 3 H 2 and CH 3 CCH are found to be similar to those in the cloud core, while SO, HCO + and HCS + are enhanced in the Radical Region by factors of ~ 5-50. It is concluded that this part of the cloud does not have very unusual chemistry. Previous results suggesting anomalous abundances are misleading, because the low-J transitions observed were enhanced in cool, dense gas.

Measurements of CS and C 34 S J=7-6 toward five of the six millimetre continuum sources in NGC 2024 were used to estimate the excitation temperatures and column densities of warm, dense gas associated with the cores. For estimated CS source sizes of ∼20 arcsec, the calculated excitation temperatures are ≥24 K, consistent with previous studies. A correlation between CS column density and hydrogen column density derived from the thermal dust continuum shows that it is self-consistent to assume internally heated cores and a close relationship between the characteristic temperatures of the CS-traced gas and the dust traced by the millimetre continuum. The nature of the individual sources is also discussed

12-arcsec resolution CO observations of the fast unipolar molecular jet in Orion B are reported, together with maps of the ambient cloud as traced by CS and C 18 O emission. The flow (which appears to originate from FIR5) consists of many clumps of gas, with sizes ≤10 15 m and velocity dispersions ∼6 km/s, which fill an almost cylindrical lobe; these clumps are probably formed locally through hydrodynamic instabilities rather than being bullets of protostellar ejecta. The flow is centrally condensed and, at the highest projected velocities (∼45 km/s), an unresolved jet of material is detected with an opening angle ∼2°

Short-term variability of the coma Levy (1990c) was detected and monitored with the International Ultraviolet Explorer (IUE) satellite observatory during August and September 1990 including 24 hr of continuous observation on 18 September. The visible lightcurve obtained on this date with the IUE Fine Error Sensor (FES) shows two distinct maxima separated by 17.0 ± 0.1 hr. However, this period cannot properly match in phase the FES data obtained during 8-hr shifts on 11 and 13 September, and suggests a decrease in apparent period of ∼1.3% per day. A similar decrease is derived from a comparison with the period derived from ground-based data taken in late August. The variation in the ultraviolet emissions of OH, CS, and CO2+, as well as that of the ultraviolet continuum (λ = 2960 A ) , was also determined from 18 consecutive long-wavelength IUE spectra taken on 18 September. From these data it is possible to model a production rate source function based on a nucleus whose activity exhibits a hemispherical asymmetry. Moreover, the ratio of gas to dust production rates is found to show a similar asymmetry. It is also found that the dust outflow velocity is about one-fourth the gas velocity. A sharp change in CO2+ brightness suggests that a subsurface region of volatiles, including CO2, may be partly responsible for the observed variability, although the origin of the decrease in period remains unexplained. CO was also observed, with a production rate 0.04 ± 0.01 that of H2O, but the long exposure time required for this measurement precluded any determination of CO variability. IUE observations made postperihelion on 9–10 January 1991 showed no variability.

Cocondensation of carbon disulfide with high-frequency discharged argon at 4 K produced carbon monosulfide and atomic sulfur, which reacted spontaneously upon annealing to form the carbon trisulfide molecule as identified from the multiplets observed in mixed (12)C, (13)C and (32)S, (34)S isotopic spectra. On the basis of isotopic substitution and theoretical frequency calculations, infrared absorptions at 1263.3 and 570.1 cm(-1) were assigned to predominantly CS stretching and bending vibrations of CS(3) in solid argon. The CS(3) molecule, which was calculated to have a singlet ground state with C(2v) symmetry, dissociated to form the weakly bound SCS-S complex upon visible light irradiation.

We present a comparative study of several molecular lines and of the dust contiunuum at 1.2mm in a pre-stellar core that is embedded in the Galactic cirrus cloud MCLD123.5+24.9. Previous studies found that the core is gravitationally stable and shows signs of inward motion. Using the Owens Valley (OVRO) and Plateau de Bure (PdB) interferometers we obtained high-angular resolution maps of the core in the carbon monosulfide CS 2-1 and the cyanoacetylene HC3N 10-9 transitions. Together with CS 5-4, C34S 3-2, and bolometer data obtained with the IRAM 30m telescope, we analyse the excitation conditions and the structural properties of the cloud. On the one hand, the new CS 2-1 observations reveal significant substructure on a scale of about 7", i.e., the beam size, corresponding to about 1050 AU at an adopted distance of 150pc. On the other hand, the interferometric observations in the HC3N 10-9 transition shows just one single well resolved clump in the inner part of the core. This core is well described by an intensity profile following from a centrally peaked volume density distribution. We find no evidence for depletion of CS onto dust grains. The inward motion seen in the CS 2-1 occurs one-sided from the middle of the filamentary cloud towards the HC3N core., Comment: 8 pages, 8 figures, accepted by A&A

Методом термодинамического моделирования теоретически изучена возможность определения серы по спектру молекулярного поглощения CS в пламенах ацетилен-воздух и ацетилен-динитрооксид. Показано, что наиболее чувствительное определение серы возможно только с использованием сильно обогащенных по топливу пламен. Рассмотрен возможный механизм образования молекул CS в пламенах. Согласно расчетам прогнозируется отсутствие матричных неспектральных помех многих катионов и анионов на аналитический сигнал серы. Выявлены также оптимальные составы пламен для определения серы по ее атомному поглощению. Теоретические расчеты хорошо подтверждают экспериментальные данные. Sulfur determination possibilities by CS molecular absorption in air-acetylene and nitrous oxide-acetylene flames were investigated. It was found that most sensitive sulfur determination is possible only highly fuel-enriched flames. Possible mechanism of CS molecular formation in flames was investigated. According to calculation, chemical interferences of most cations and anions on sulfur analytical signal were not found. Optimum flames compositions for sulfur determination by atomic absorption was revealed. Theoretical calculations are in a good agreement with experimental data.

A new method for the determination of sulfur forms in wine, i.e., free SO(2), total SO(2), bound SO(2), total S, and sulfate, is presented. The method is based on the measurement of the carbon monosulfide (CS) molecular absorption produced in a conventional air-acetylene flame using high-resolution continuum source absorption spectrometry. Individual sulfur forms can be distinguished because of the different sensitivities of the corresponding CS molecular absorption. The sensitivity of free SO(2) is about three times higher than the value for bound SO(2) and sulfate. The method makes use of procedures similar to those used in classic reference methods. Its performance is verified by analyzing six wine samples. Relative standard deviations are between 5 and 13% for free SO(2) and between 1 and 3% for total SO(2). For the validation of the accuracy of the new method, the results are compared with those of reference methods. The agreement of the values for total SO(2) with values of the classic method is satisfactory: five out of six samples show deviations less than 16%. Due to the instability of free SO(2) in wine and the known problems of the used reference method, serious deviations of the free SO(2) results are found for three samples. The evaluation of the limits of detection focuses on the value for free SO(2), which is the sulfur form having by far the lowest concentration in wine. Here, the achievable limit of detection is 1.8 mg L(-1). [figure: see text] Detection of non-metal elements using continuum source flame absorption spectrometry.

Context. Over the next few years, Alma and Herschel missions will open the universe to high spatial and spectral resolution studies at infrared and sub-millimeter wavelengths. Modeling of the observed spectra will require accurate radiative and collisional rates on species of astrophysical interest. Aims. The present paper focuses on the calculation of new rate coefficients among the 31 first rotational levels of the CS molecule in collision with He for temperatures ranging from 10 K to 300 K. Methods. A new 2D potential energy surface for the CS-He system, calculated at a CSr-distance frozen at its experimental equilibrium distance was obtained with accurate quantum chemistry methods. Quantum close-coupling calculations lead to collisional cross sections and rate coefficients. Results. The new rate coefficients are calculated up to 300 K. These new coefficients differ significantly from previously published ones. The consequences for astrophysical models are evaluated.

Determination of sulfur in wine is an important analytical task, particularly with regard to food safety legislation, wine trade, and oenology. Hitherto existing methods for sulfur determination all have specific drawbacks, for example high cost and time consumption, poor precision or selectivity, or matrix effects. In this paper a new method, with low running costs, is introduced for direct, reliable, rapid, and accurate determination of the total sulfur content of wine samples. The method is based on measurement of the molecular absorption of carbon monosulfide (CS) in an ordinary air-acetylene flame by using a high-resolution continuum-source atomic-absorption spectrometer including a novel high-intensity short-arc xenon lamp. First results for total sulfur concentrations in different wine samples were compared with data from comparative ICP-MS measurements. Very good agreement within a few percent was obtained.

Irradiation of gaseous carbon disulfide [CS2(g)] at 313 nanometers produces a dark brown aerosol of (CS2)x. Its thermal decomposition products include disulfur (S2), carbon monosulfide (CS), and (CS)x. The photopolymerization process is accompanied by a large mass-independent isotopic fractionation of sulfur (a 5 to 10 per mil sulfur-33 excess and a 61 to 84 per mil sulfur-36 deficit). Excess sulfur-33 has been observed in several classes of meteorites. Photochemical production of (CS2)x may be important in the origin and evolution of cosmochemical environments such as the presolar nebula, meteorites, asteroids, and planetary atmospheres.

Dissociative electron attachment to the unstable CS molecule, carbon monosulfide, produced in a microwave discharge of carbon disulfide and helium has been observed in the electron energy range 0–10 eV. The S− ion is formed in two electron attachment bands with maxima at 5.43 ± 0.15 eV and ~6.70 ± 0.15 eV and C− is formed in a band with a maximum of ~6.40 ± 0.15 eV. Absolute cross sections for these processes are estimated to be 0.025, 0.003 and 0.002 A2 respectively. These interactions of CS with low energy electrons will play a role in technological plasmas containing carbon and sulfur and extraterrestrial environments where electrons are present with 5–7 eV energy. New results are also presented for the molecules S2O, C3S2 and S2F, which were also formed in the microwave discharge. For S2O the previously reported S− band at 1.8 ± 0.3 eV is confirmed and a new O− attachment band at ~5.4 eV is tentatively assigned to S2O. Ionization thresholds of C3S2 (9.4 ± 0.3 eV) and S2F (10.3 ± 0.4 eV) have been measured, apparently for the first time.

The region containing the two young stellar objects, Haro 4-255 and Haro 4-255 FIR, has been studied through single-dish and aperture-synthesis CS (1-0) observations. We have detected an intense CS outflow, whose FWZI velocity extent is about 9 km s -1 , in the single-dish observations. The distribution of the blue CS lobe is appreciably different from that of the blue CO lobe, whereas the distribution of the red CS lobe is similar to that of the red CO lobe. The CS abundance in this outflow seems to be enhanced nearly by one order of magnitude, although that in the quiescent gas shows a more normal value. The mass of the CS outflow is appreciably larger than that of the CO outflow, while the mechanical luminosity of the CS outflow is smaller than that of the CO outflow

An accurate fluorescence efficiency of the CS(0,0) band and the lifetime of CS have been calculated at 1 AU heliocentric distance. Model-independent CS column densities and production rates are determined from derived fluorescent emission rates (g-factors) and lifetimes for 15 comets: Austin (1982g), Borrelly (1980i), Bradfield (1979X), Crommelin (1983n), Encke (1980), Encke (1984), Giacobini-Zinner (1984e), Halley (1982i), IRAS-Araki-Alcock (1983d), Meier (1980q), Panther (1980u), Stephan-Oterma (1980g), Tuttle (1980h), West (1975n), and Wilson (1986l).

The density and temperature structure of the bright-rimmed cometary globule IC 1396E is estimated, and the possibility that recent internal star formation was triggered by the ionization front in its southern surface is assessed. On the basis of NH3 data, gas temperatures in the globule are found to increase outward from the center, from a minimum of 17 K in its tail to a maximum of 26 K on the surface most directly facing the stars ionizing IC 1396. On the basis of a microturbulent radiative transfer code to model the radial dependence of the CS line intensities, and also the intensities of the optically thin 2-1 and 5-4 lines toward the cloud center, a radial density dependence of r exp -1.55 to r exp -1.75 is found.

We present submillimeter-wave single dish and millimeter-wave interferometric observations of the central core region of the far-infrared source IRAS 16293-2422. High-resolution millimeter continuum and CS images of IRAS 16293 reveal it to be a young binary system surrounded by a slowly rotating circumbinary shell of material. We use single dish CS observations in conjunction with the interferometric CS observations to probe the dynamics and physical properties of the gas associated with the system

We observe the dense gas in the L1204/S140 molecular complex using CS(J=1-0) and NH 3 . The large-scale CS(J=1-0) maps show that L1204 is formed by three filamentary clouds, each being fragmented into cores of a few hundred solar masses and surrounded by low-level emission. The most prominent core is associated with S140, a well-known high-mass star-forming region. The star-forming activity, however, is not restricted to the vicinity of S140, but extends throughout the complex; very red IRAS sources lie close to most of the cores and molecular outflows have been detected in half of them

The protoplanetary nebula CRL 2688 with 14-arcsec resolution was observed, and the envelope in CO, (C-13)O, CS, and H(C-13)N was mapped. The submillimeter lines show strong emission from two components of the envelope: a cold, dense, optically thick slow wind and a warm, optically thin fast wind. In the maps, the slow wind appears compact and circularly symmetric. A mass-loss rate in the fast wind of 0.00002 solar mass/yr is estimated, if the wind was continuous. The C-12/C-13 ratio in the fast wind is 5, compared to about 20 in the slow wind. The value in the HCN/CO abundance ratio may be lower in the fast wind than in the slow wind. It is argued that the velocity gradients are not caused by rotation, but rather by asymmetries in the envelope associated with the fast wind.

The «50 km s −1 » molecular cloud (M-0.02-0.07) near the Galactic center has been mapped in the CS J=7-6 and 5-4 rotational transitions. In addition, mid-infrared fine-structure lines of [Ne II], [Ar III], and [S IV] have been observed toward the compact H II regions located near the cloud's core.

Radiative transfer models of low-mass dense cores as depicted in two theoretical models of protostellar collapse, the Larson-Penston flow and the theory of Shu and coworkers based on the «inside-out collapse» model, are presented. In particular, line profiles of the first three rotational transitions of the CS molecule are calculated for hypothetical dense cores evolving according to these theories. The results are compared with CS observations of nearby dense cores. It is shown that the Larson-Penston flow overestimates the velocity width of the CS lines by a large margin and cannot be reconciled with the observations

High-resolution millimeter-wave aperture synthesis images of the CS J = 2 → 1 and dust continuum emission toward the young star HL Tauri have been combined with single-dish spectra of the higher J CS transitions in order to probe the chemical and physical structure of circumstellar material in this source. We find that the extended molecular cloud surrounding HL Tau is similar to other Taurus dark cloud cores, having T_(kinetic) ≈ 10-20 K, n_(H2) ≈ 10^4-10^5 cm^(-3) , and x(CS) = N(CS)/N(H_2) ≈ (1-2) x 10^(-8). In contrast, the gas-phase CS abundance in the circumstellar disk is depleted by factors of at least 25-50, and perhaps considerably more. These results are consistent with substantial depletion onto grains, or a transition from kinetically controlled chemistry in the molecular cloud to thermodynamically controlled chemistry in the outer regions of the circumstellar disk. Dust continuum emission at 3.06 mm, although unresolved in a 3".0 beam, appears centered on the stellar position; combined with other millimeter-wave measurements its intensity indicates an emissivity index of β = 1.2 ± 0.3. This β may reflect grain growth via depletion and aggregation or compositional evolution, and suggests that the 3.06 mm dust opacity exceeds unity within 8-10 AU of HL Tauri. Even at millimeter and submillimeter wavelengths, observational studies of other high dipole moment molecules in circumstellar disks may also be hampered by the combination of grain mantle depletion and dust opacity structure in sources viewed nearly edge-on.

The dark molecular cloud L134N is observed at millimeter wavelengths in the CS (J = 3-2), OCS (J = 7-6), and HDO (1 sub 11-1 sub 10) transitions. The CS (J = 3-2) transition was observed at four positions within the cloud, while the other two transitions were observed at one position each. Fractional abundances in the LTE approximation are calculated for each emission line detected. L134N appears to have a high-density core characterized by NH3, C3H2, and H(C-13)O(+) emission maps. A lower density envelope characterized by C(0-18), CS (J = 2-1), and SO emission surrounds the core. There appears to be a gas-phase oxygen abundance gradient in L134N with atomic oxygen depleted in the high-density core. Observed molecular distributions within L134N can be explained by a model in which chemical and physical processes in icy-dust-grain mantles influence the gas-phase molecular abundances.

We have carried out a study of the NGC 2071 (North) molecular cloud in the 3 mm wavelength transitions of CO, 13 CO, C 18 O, CS, and HCO + using the FCRAO 14 m telescope. We find that the distribution of CS and C 18 O, two tracers that are widely used to trace dense gas in molecular clouds, are very different, and that they both differ appreciably from the previously published distribution of NH 3

The results of a survey for CS J=7→6 emission towards 179 star-forming regions, selected by the presence of an H 2 O maser with an accurate position, are presented. The line was detected in 104 sources (58%); the detections have a mean T * R of 2.9 K and a mean ∫T * R dv of 28 K km/s. Using LVG excitation calculations, the densities are estimated between log (n) of 4.7 and 6.7 for a CS 7→6 optical depth of 1