L. Margulès's research while affiliated with French National Centre for Scientific Research and other places

Publications (284)

Article
Full-text available
Context. Methanimine, CH 2 NH, and ethanimine, CH 3 CHNH, were both detected in the interstellar medium (ISM), the former in the 1970s and the latter nearly a decade ago. By analogy with nitriles, for which hydrogen cyanide, acetonitrile, and ethyl cyanide are the most abundant, n-propanimine was suggested as a candidate for detection in the ISM. A...
Article
Context. One of the biggest unsolved mysteries of modern astrochemistry is understanding chemical formation pathways in the interstellar medium (ISM) and circumstellar environments. The detections (or even nondetections) of molecules composed of low-abundance atomic species (such as S, P, Si, and Mg) may help to constrain chemical pathways. Thioace...
Article
The rotational spectrum (4-40 GHz and 50-330 GHz) has been measured and analyzed for trifluoroacetaldehyde, also known as fluoral (CF3CHO), which is one of the degradation products of the fluorinated contaminants emitted into the atmosphere. The complexity of the spectroscopic analysis of this molecule arises from the strong coupling between the in...
Article
Context. Di-deuterated molecules are observed in the earliest stages of star formation at abundances of a few percent relative to their nondeuterated isotopologs, which is unexpected considering the scarcity of deuterium in the interstellar medium. With sensitive observations leading to the detection of a steadily increasing number of di-deuterated...
Preprint
Full-text available
Accurate quantification of the column density of di-deuterated methanol is a key missing puzzle piece in the otherwise thoroughly constrained family of D-bearing methanol in the deeply embedded low-mass protostellar system and astrochemical template source IRAS16293-2422. A spectroscopic dataset for astrophysical purposes is built for CHD$_{2}$OH a...
Article
Context. One of the biggest unsolved mysteries of modern astrochemistry is understanding chemical formation pathways in the interstellar medium (ISM) and circumstellar environments. The detections (or even nondetections) of molecules composed of low-abundance atomic species (such as S, P, Si, and Mg) may help to constrain chemical pathways. Thioace...
Preprint
Full-text available
Thioacetamide (CH3CSNH2) is the sulfur analog to acetamide (CH3CONH2) and it is a viable candidate to search for in astronomical environments specifically toward regions where other S-bearing molecules have been found and, if possible, that also contain a detection of CH3CONH2. If detected, it would not only continue to expand the view of molecular...
Article
We have recently analyzed the broadband millimeter-wave rotational spectrum of chloroform CH³⁵Cl3 in the v3=v6=1 (E symmetry) and v6=2 (A1+E) vibrational excited. In the present work, we have used the same spectrum (recorded between 150-330 and 360-660 GHz) for a rotational analysis of the v2=1 and v3=2 A1 states of the same molecule, together with...
Article
New transitions are reported in the submillimeter wave, terahertz, and far-infrared rotation-torsion spectrum of doubly-deuterated methanol CD2HOH. The newly assigned transitions allow us to spectroscopically characterize torsional states with 0⩽K⩽12 and 0⩽vt⩽2. Three line position analyses are carried out. In the first one, restricted to rotation-...
Preprint
Full-text available
Peptide bonds, as the molecular bridges that connect amino acids, are crucial to the formation of proteins. Searches and studies of molecules with embedded peptide-like bonds are thus important for the understanding of protein formation in space. Here we report the first tentative detection of propionamide (C2H5CONH2), the largest peptide-like mole...
Article
Full-text available
Context. In 2013, we published the first rotational analysis and detection of mono-deuterated dimethyl ether in the solar-type protostar IRAS 16293-2422 with the IRAM 30 m telescope. Dimethyl ether is one of the most abundant complex organic molecules in star-forming regions, and its D-to-H (D/H) ratios are important to understand its chemistry and...
Preprint
In 2013, we have published the first rotational analysis and detection of mono-deuterated dimethyl ether in the solar-type protostar IRAS 16293-2422 with the IRAM 30m telescope. Dimethyl ether is one of the most abundant complex organic molecules (COMs) in star-forming regions and their D-to-H (D/H) ratios is important to understand its chemistry a...
Preprint
The first excited torsional state of the chiral molecule propylene oxide, $\mathrm{CH_{3}C_{2}H_{3}O}$, is investigated from millimeter up to sub-millimeter wavelengths (75-950 GHz). The first excited vibrational mode of propylene oxide, $\upsilon_{24}$, is analysed using the programs ERHAM and XIAM. Rotational constants and tunneling parameters ar...
Article
Three compounds with a C3H6O2 formula have been detected in the Interstellar Medium (ISM): ethyl formate (CH3CH2OC(O)H), methyl acetate (CH3OC(O)CH3) and very recently hydroxyacetone (CH3C(O)CH2OH). The higher thermodynamic stability of another isomer, the propanoic acid (CH3CH2C(O)OH), clearly suggests that this molecule should be considered as a...
Article
Full-text available
Context. Among the six atoms of N-containing molecules with the formula of CH 3 NO, only formamide (H 2 NCHO), the most stable structural isomer, has been detected in the interstellar medium (ISM). The formaldoxime isomer may be formed, for example, by the reaction of formaldehyde (H 2 CO) or methanimine (H 2 CNH) and hydroxylamine (H 2 NOH), which...
Article
The first excited torsional state of the chiral molecule propylene oxide, CH3C2H3O, is investigated from millimeter up to sub-millimeter wavelengths (75-950 GHz). The first excited vibrational mode of propylene oxide, υ24, is analysed using the programs ERHAM and XIAM. Rotational constants and tunneling parameters are provided, and a description of...
Article
Using the Yebes 40m and IRAM 30m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The lines have been seen towards the cold dense cores TMC-1, L483, L1527, and L1544. High level of theory ab initio calculations indicate that the best possible candidate is the acetyl cation, CH3C...
Preprint
Full-text available
Using the Yebes 40m and IRAM 30m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The lines have been seen towards the cold dense cores TMC-1, L483, L1527, and L1544. High level of theory ab initio calculations indicate that the best possible candidate is the acetyl cation, CH3C...
Article
Full-text available
Context. S-methyl thioformate CH 3 SC(O)H is a monosulfur derivative of methyl formate, a relatively abundant component of the interstellar medium (ISM). S-methyl thioformate being, thermodynamically, the most stable isomer, it can be reasonably proposed for detection in the ISM. Aims. This work aims to experimentally study and theoretically analyz...
Conference Paper
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A new millimeter-wave Fourier transform emission spectrometer is described. The spectrometer covers the frequency range from 50 to 330 GHz. Main feature of the spectrometer is application of the single radiation source both as generator of short polarizing pulses and as a local oscillator for heterodyne receiving system. Such design provides cohere...
Preprint
Full-text available
Context. The majority of sulfur-containing molecules detected in the interstellar medium (ISM) are analogs of oxygen-containing compounds. Propynal was detected in the ISM in 1988, hence propynethial, its sulfur derivative, is a good target for an ISM search. Aims. Our aim is to measure the rotational spectrum of propynethial and use those measurem...
Preprint
Thioformamide NH2CHS is a sulfur-bearing analog of formamide NH2CHO. The latter was detected in the interstellar medium back in the 1970s. Most of the sulfur-containing molecules detected in the interstellar medium are analogs of corresponding oxygen-containing compounds. Therefore, thioformamide is an interesting candidate for a search in the inte...
Article
Full-text available
Context. Thioformamide NH 2 CHS is a sulfur-bearing analog of formamide NH 2 CHO. The latter was detected in the interstellar medium back in the 1970s. Most of the sulfur-containing molecules detected in the interstellar medium are analogs of corresponding oxygen-containing compounds. Therefore, thioformamide is an interesting candidate for a searc...
Article
Full-text available
Context. The majority of sulfur-containing molecules detected in the interstellar medium (ISM) are analogs of oxygen-containing compounds. Propynal was detected in the ISM in 1988, hence propynethial, its sulfur derivative, is a good target for an ISM search. Aims. Our aim is to measure the rotational spectrum of propynethial and use those measurem...
Preprint
Observations of ammonia in interstellar environments have revealed high levels of deuteration, and all its D-containing variants, including ND$_3$, have been detected in cold prestellar cores and around young protostars. The observation of these deuterated isotopologues is very useful to elucidate the chemical and physical processes taking place du...
Article
The rotational spectra of ³²S¹⁶O¹⁸O and ³²S¹⁸O2 have been recorded from 150 GHz to 1.52 THz. Accurate rotational parameters have been determined for the ground state and the vibrational states v2 = 1 and v1 = 1, as well as v2 = 2 for ³²S¹⁸O2. The quality of the fits using the A- or S-type reductions for the Watson Hamiltonian is discussed. An exper...
Article
We present a millimeter-wave Fourier transform emission spectrometer whose design is based on the application of a direct digital synthesizer (DDS) up-converted into the Ku-band with subsequent frequency multiplication. The spectrometer covers the frequency range from 50 GHz to 110 GHz and from 150 GHz to 330 GHz. Owing to the fast frequency switch...
Article
We present a new study of the millimeter and submillimeter wave spectra of the thioacetaldehyde molecule, CH3CHS, a sulfur-bearing analog of the ubiquitous interstellar molecule acetaldehyde (CH3CHO). Here, we present a laboratory investigation aimed at determining accurate spectroscopic parameters for CH3CHS to enable astronomical searches for thi...
Article
The overtone v6=2 (∼520 cm⁻¹) and combination v3=v6=1 (∼627 cm⁻¹) vibrational levels of chloroform CH³⁵Cl3 have been studied by millimeter wave spectroscopy, in the regions 150-330 and 360-660 GHz, corresponding to J=22-49 and 55-99. Like the v6=1 fundamental vibration, the v3=v6=1 combination level has an accidentally small value of C-B-Cζ ∼ −0.00...
Article
Full-text available
Context. Ketene was detected in the interstellar medium (ISM) in 1977. Until now, only one derivative, the ketenyl radical, has been observed in this medium. Due to its large dipole moment value, cynaoketene is one of the best candidates for possible ketene derivative detection. Aims. To date, the measurements of the rotational spectra have been li...
Article
The rotational spectrum of an organoarsenic compound, methylarsine, CH3AsH2, was studied in the frequency range 10–80 GHz using the Stark-modulated spectrometer in Oslo, and in the frequency range 150–660 GHz using the Lille spectrometer. The experimental work was augmented by high-level ab initio calculations. The analysis of large amplitude torsi...
Article
We present a new global study of the millimeter, submillimeter and far-infrared (FIR) spectra of dimethylsulfide ((CH3)2S). New microwave measurements have been carried out between 49 and 660 GHz using spectrometers in IRA NASU (Ukraine), and PhLAM Lille (France). Pure rotational transitions belonging to the three lowest torsional states (ν11,ν15)...
Article
We present a new global study of the millimeter, submillimeter and far-infrared (FIR) spectra involving the three lowest torsional states of acetone ((CH3)2CO). New microwave measurements have been carried out between 34 and 940 GHz using spectrometers in IRA NASU (Ukraine), and PhLAM Lille (France). The FIR spectrum of acetone has been recorded on...
Research
Full-text available
PCMI in a nutshell: The ``Programme National de Physique et Chimie du Milieu Interstellaire'' is a French science network, led and supported by the CNRS Institutes of Universe Sciences (INSU), Physics (INP), and Chemistry (INC), and by CNES, and the CEA. The community gathers about 350 astrophysicists, physicists, and chemists from nearly 50 labora...
Article
Context . Detection of deuterated species may provide information on the evolving chemistry in the earliest phases of star-forming regions. For molecules with two isomeric forms of the same isotopic variant, gas-phase and solid-state formation pathways can be differentiated using their abundance ratio. Aims . Spectroscopic databases for astrophysic...
Article
Full-text available
Context . Nitriles constitute almost 20% of the molecules observed in the interstellar medium, whereas only one dinitrile and one isocyanonitrile compound have been detected up to now. The lack of detections of such compounds may be partially explained by the lack of accurate spectroscopic data on their rotational spectra. Aims . Two small seven-at...
Article
Doublet, triplet and quartet hyperfine splitting patterns have been observed in the E-species component of the first excited (v t = 1) torsional state of CH 3 OH. Four series of lines dominate the available data: (i) a K = 6 ← 7, Q branch series of quartets, with 7 ≤ J ≤ 15; (ii) a K = 3 ← 2, Q branch series, with 3 ≤ J ≤ 18, which starts as quarte...
Article
Full-text available
Context: The analysis of isomeric species of a compound observed in the interstellar medium (ISM) is a useful tool to understand the chemistry of complex organic molecules. It could, likewise, assist in the detection of new species. Aims: Our goal consists in analyzing one of the two most stable species of the C3H4O family, methyl ketene, whose...
Article
This study is aimed at the evaluation of THz gain properties in an optically pumped NH3 gas. NH3 molecules undergo rotational-vibrational excitation by mid-infrared (MIR) optical pumping provided by a MIR quantum cascade laser (QCL) which enables precise tuning to the NH3 infrared transition around 10.3 µm. Pure inversion transitions, (J = 3, K = 3...
Article
Cyanoacetylene, HCC-CN is a ubiquitous molecule in the Universe. However, its interstellar chemistry is not well understood and its understanding requires laboratory data including rotational spectroscopy of possible products coming from a reaction with another compounds. In this study we present the first spectroscopic characterization of gauche c...
Article
Full-text available
We report the detection in space of a new molecular species which has been characterized spectroscopically and fully identified from astrophysical data. The observations were carried out with the 30m IRAM telescope. The molecule is ubiquitous as its $J$=2$\rightarrow$1 transition has been found in cold molecular clouds, prestellar cores, and shocks...
Article
Full-text available
We report the detection of interstellar methoxymethanol (CH$_3$OCH$_2$OH) in ALMA Bands 6 and 7 toward the MM1 core in the high-mass star-forming region NGC 6334I at ~0.1" - 1" spatial resolution. A column density of 4(2) x $10^{18}$ cm$^{-2}$ at $T_{ex}$ = 200 K is derived toward MM1, ~34 times less abundant than methanol (CH$_3$OH), and significa...
Article
Context. About 40 cyanide compounds have been detected in the interstellar medium, but only 3 examples of organic isocyanide compounds were observed in this medium. Ethyl isocyanide is one of the best candidates for possible detection. Aim. To date, measurements of rotational spectra are limited to 40 GHz. The extrapolation of the prediction in the...
Article
Methylglyoxal is a secondary product of oxidation of isoprene and as such one of the most abundant α-dicarbonyls present in the atmosphere. Due to its low vapor pressure, it is highly suspected to be a secondary organic aerosols precursor. The rotational spectrum of Methylglyoxal in its vibrational ground state has been reinvestigated in the 4-500...
Article
Aminoacetonitrile (NH2CH2CN) was detected in the interstellar medium (ISM) one decade ago in the course of a spectral survey of the hot molecular core Sagittarius (Sgr) B2(N) with the IRAM 30 m telescope. With the advent of sensitive telescopes such as the Atacama Large Millimeter/submillimeter Array (ALMA), the degree of chemical complexity in the...
Article
Methoxymethanol, CH3OCH2OH is a very interesting candidate for the detection in the interstellar medium since it can be formed by the recombination reaction between two radicals considered as intermediates in the methanol formation: CH3O (already detected in the ISM) and CH2OH. It could be also formed by addition of CH3O on formaldehyde (another ab...
Research Proposal
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Les études du milieu interstellaire cherchent à explorer la croissance de la complexité et des structures dans l'espace et leurs liens avec la formation des étoiles et l'évolution des galaxies. Les défis associés pour la prochaine décennie imposent de modéliser des systèmes complexes à la frontière entre physique moléculaire et physique du solide....