Bop Cheikh Tidiane

Nantes Université | UNIV Nantes · Interdisciplinary Chemistry, Synthesis, Analysis, Modeling (CEISAM)

In this present paper, we focus on the determination of the rotational excitation rate coefficients of the first observed molecule containing noble gas 36ArH+ isotope by He. Hence, we present the first potential energy surface (PES) of ArH+ −He van der Waals system. The interaction PES of the ArH+(X1Σ+)−He(1S) complex is calculated by the ab initio...

The potential energy surface is computed at the explicitly correlated coupled cluster with simple, second and perturbative triple excitation method (CCSD(T)–F12) in connection with the augmented–correlation consistent–polarized valence triple zeta (aug–cc–pVTZ) Gaussian basis set for the NeH+ −He system. The calculations were performed by first tak...

Collisional energy transfer under cold conditions is of great importance from the fundamental and applicative point of view. Here, we investigate low temperature collisions of the SH⁻ anion with He. We have generated a three-dimensional potential energy surface (PES) for the SH⁻(X1Σ+)-He(¹S) van der Waals complex. The ab initio multi-dimensional in...

Phosphorus bearing molecules have been discovered in the circumstellar and interstellar media. Modelling accurately their abundance requires computations of rate coefficients induced by collision with He and H2 (i.e the most abundant gaseous components). These calculations may be carried out by first determining high accurate potential energy surfa...

Investigating molecular excitation induced by collisions requires the prior determination of accurate analytical potential energy surfaces for the colliding partners. For carbon-chain molecules, such as cyanopolyynes, this has been a longstanding challenge, resulting in the absence of rate coefficients for HC5N, HC7N, HC9N, and others, induced by c...

Recent astronomical observations revealed an increasing molecular complexity in the interstellar medium through the detection of a series of large cyclic carbon species. To correctly interpret these detections, a complex analysis is necessary that takes into account the non-local thermodynamic equilibrium (non-LTE) conditions of the emitting media...

Recent astronomical observations revealed an increasing molecular complexity in the interstellar medium through the detection of a series of large cyclic carbon species. To correctly interpret these detections, a complex analysis is necessary that takes into account the non-local thermodynamic equilibrium (non-LTE) conditions of the emitting media...

The protonated form of hydrogen cyanide, HCNH$^+$, holds significant importance in astrochemistry, serving as an intermediate species in ion-neutral reactions occurring in the cold molecular clouds. Although it plays a crucial role in the chemistry of HCN and HNC, the excitation rate coefficients of this molecular cation by the dominant interstella...

The protonated form of hydrogen cyanide, HCNH + , holds significant importance in astrochemistry, serving as an intermediate species in ion-neutral reactions occurring in the cold molecular clouds. Although it plays a crucial role in the chemistry of HCN and HNC, the excitation rate coefficients of this molecular cation by the dominant interstellar...

Context . The global context of making numerous data produced by researchers available requires collecting and organising the data, assigning meaningful metadata, and presenting the data in a meaningful and homogeneous way. The BASECOL database, which collects inelastic rate coefficients for application to the interstellar medium and to circumstell...

Context. Protonated hydrogen cyanide, HCNH ⁺ , plays a fundamental role in astrochemistry because it is an intermediary in gas-phase ion-neutral reactions within cold molecular clouds. However, the impact of the environment on the chemistry of HCNH ⁺ remains poorly understood. Aims. We aim to study HCNH ⁺ , HCN, and HNC, as well as two other chemic...

Protonated hydrogen cyanide, HCNH$^{+}$, plays a fundamental role in astrochemistry because it is an intermediary in gas-phase ion-neutral reactions within cold molecular clouds. However, the impact of the environment on the chemistry of HCNH$^{+}$ remains poorly understood. With the IRAM-30 m and APEX-12 m observations, we report the first robust...

Context. In the centre of pre-stellar cores, deuterium fractionation is enhanced due to low temperatures and high densities. Therefore, the chemistry of deuterated molecules can be used to probe the evolution and the kinematics in the earliest stages of star formation. Aims. We analyse the deuterium fractionation of simple molecules, comparing the...

In the centre of pre-stellar cores, deuterium fractionation is enhanced due to the low temperatures and high densities. Therefore, the chemistry of deuterated molecules can be used to study the earliest stages of star formation. We analyse the deuterium fractionation of simple molecules, comparing the level of deuteration in the envelopes of the pr...

Protonated molecules have been increasingly detected in the interstellar medium (ISM) and usually astrochemical models fail at reproducing the abundances derived from observational spectra. Rigorous interpretation of detected interstellar emission lines requires prior calculations of collisional rate coefficients with H_2 and He, i.e. the most abun...

Context. HCN, HNC, and their isotopologues are ubiquitous molecules that can serve as chemical thermometers and evolutionary tracers to characterize star-forming regions. Despite their importance in carrying information that is vital to studies of the chemistry and evolution of star-forming regions, the collision rates of some of these molecules ha...

HCN, HNC, and their isotopologues are ubiquitous molecules that can serve as chemical thermometers and evolutionary tracers to characterize star-forming regions. Despite their importance in carrying information that is vital to studies of the chemistry and evolution of star-forming regions, the collision rates of some of these molecules have not be...

Tricarbon and pentacarbon monoxides have been detected towards TMC-1 with relatively important abundances. Understanding their chemical formation of these molecules requires interpreting their observational spectra by mean of non-local thermodynamical equilibrium modelling. For this purpose, we report rate coefficients of CCCO and CCCCCO induced by...

The isomers of HCCCN, namely HCCNC and HNCCC, are widely observed in the interstellar medium and in circumstellar envelopes. Their abundance has been determined under the assumption of local thermodynamic equilibrium (LTE) conditions or non-LTE radiative transfer models, but in considering the collisional excitation of HCCCN as the same for all iso...

Due to the lack of specific collisional data, the abundance of NS+ in cold dense interstellar clouds was determined using collisional rate coefficients of CS as substitute. To better understand the chemistry of sulfur in the interstellar medium, further abundance modeling using the actual NS+ collisional rate coefficients are needed. For this purpo...

The recent detections of CNCN and HNCCN^+ are seen as further evidence of the large abundance of NCCN in the interstellar medium. The accurate determination of the abundance of these chemically related compounds from the observational spectra requires the prior calculation of collisional rate coefficients. In this work, we aimed at computing hyperf...

The two species considered here, O2 (oxygen molecule) and Ar (argon-atom), are both abundant components of Earth's atmosphere and hence familiar collision partners in this medium. O2 is quite reactive and extensively involved in atmospheric chemistry, including Chapman's cycle of the formation and destruction of ozone; while Ar, like N2, typically...

The Pan-African School for Emerging Astronomers (PASEA) is an innovative short course for African university students, held by an African-led international collaboration. PASEA aims to build a critical mass of astronomers in Africa and exchange ideas about teaching across continents.

Cyanoacetylene molecules are widespread in the interstellar medium (ISM) and several of its isomers have been detected in cold molecular clouds and circumstellar gas. Accurate estimates of the abundance ratio of cyanoacetylene isomers may provide deep insight into their environment. Such knowledge requires rigorous modeling of the emission spectra...

Several phosphorus bearing molecules, such as phosphine of interest here, have been detected in astrophysical media. In the aim of satisfying the precision required by the astro-physical community, we report the rate coefficients of PH 3 in collision with helium from low to moderate temperature. Thus, we constructed the first three dimensional pote...

We present the results from four stellar occultations by (486958) Arrokoth, the flyby target of the New Horizons extended mission. Three of the four efforts led to positive detections of the body, and all constrained the presence of rings and other debris, finding none. Twenty-five mobile stations were deployed for 2017 June 3 and augmented by fixe...

The Chapman cycle describes the various steps in the ongoing formation and destruction of stratospheric ozone. A key step in the formation process is the stabilization of metastable ozone molecules through collisions with a third body, usually an inert collider such as N2 or Ar. The "ozone isotopic anomaly" refers to the observation of larger-than-...

We present the results from four stellar occultations by (486958) Arrokoth, the flyby target of the New Horizons extended mission. Three of the four efforts led to positive detections of the body, and all constrained the presence of rings and other debris, finding none. Twenty-five mobile stations were deployed for 2017 June 3 and augmented by fixe...

Sulfur bearing nitrogenous compounds have been observed in space over this last decade. Modeling their abundances has been done using rate coefficients of isoelectronic molecules. In order to satisfy the astrophysical precision required, we report the actual rate coefficients of NS + induced by collision with the most abundant interstellar species...

Sulfur bearing nitrogenous compounds have been observed in space over this last decade. Modeling their abundances has been done using rate coefficients of isoelectronic molecules. In order to satisfy the astrophysical precision required, we report the actual rate coefficients of NS+ induced by collision with the most abundant interstellar species (...

Rotational excitation of the interstellar HC$_2$NC and HNC$_3$ molecules, two isomers of HC$_3$N, induced by collisions with H$_{2}$ is investigated at low collision energy using a quantum time-independent approach. The scattering calculations are based on new high-level \emph{ab initio} 4-dimensional (4D) potential energy surfaces (PESs) computed...

The ro-vibrational transitions of NaH are crucially needed for the control of photo-association processes resulting from its formation and for accurately modeling the NaH abundance in space. In this work, we constructed new PESs of the NaH-He system. The potentials were computed at the CCSD(T)-F12/ cc-pVTZ level of theory. Each of the PESs presents...

Aluminium hydroxide (AlOH) is ubiquitous in the interstellar medium. However, there are no reliable data available in the literature that can be used to interpret the observations. Therefore, in this paper, we deal with the rotational rate coefficients of AlOH induced by collision with helium. The potential energy surface of the AlOH–He complex was...

Nitriles have been identified in space. Accurately modelling their abundance requires calculations of collisional rate coefficients. These data are obtained by first computing potential energy surfaces (PES) and cross-sections using high accurate quantum methods. In this paper, we report the first interaction potential of the HNCCN +-He collisional...

Phosphorus bearing molecules have been discovered in the circumstellar and interstellar media. Modeling their abundance accurately requires computations of rate coefficients induced by collision with He and H 2 (i.e., the most abundant gaseous components). These calculations may be carried out by first determining highly accurate potential energy s...

Rotational energy transfer of cesium fluoride (CsF) induced by collision with helium (He).