Search

The anions C |$_7$| N |$^-$| and C |$_{10}$| H |$^-$| are the two longest of the linear (C,N)-bearing and (C,H)-bearing chains that have so far been detected in the interstellar medium (ISM). In order to glean information on their collision-induced rotational state-changing processes, we analyse the general features of new ab initio potentials describing the interaction of both linear anions with H |$_2$|⁠ , one of the most abundant partners in their ISM environment. We employ an artificial neural network fit of the reduced-dimensionality potential energy surface for C |$_7$| N |$^-$|⁠...H |$_2$| interaction and discuss in detail the spatial features in terms of multipolar radial coefficients. For the C |$_{10}$| H |$^-$|⁠...H |$_2$| interaction, we use the initial grid of two-dimensional raw points to generate by quadrature the Legendre expansion directly, further including the long-range terms as discussed in the main text. Quantum scattering calculations are employed to obtain rotationally inelastic cross-sections, for collision energies in the range of 10 |$^{-4}$| to 400 cm |$^{-1}$|⁠. From them we generate the corresponding inelastic rate coefficients as a function of temperature covering the range from 10 to 50 K. The results for the rate coefficients for the longest cyanopolyyne are compared with the earlier results obtained for the smaller terms of the same series, also in collision with H |$_2$|⁠. We obtain that the inelastic rate coefficients for the long linear anions are all fairly large compared with the earlier systems. The consequences of such findings on their non-equilibrium rotational populations in interstellar environments are illustrated in our conclusions. [ABSTRACT FROM AUTHOR]

By extending an earlier study [Gianturco et al., J. Chem. Phys. 154, 054311 (2021)] on the purely rotational excitation of HeH+ by He atoms, we report in this paper integral cross sections and rate coefficients for rovibrational excitation and de-excitation processes in HeH+ due to collisions with He. The data were obtained using a new ab initio potential energy surface that includes the vibrational degree of freedom. The results are compared with those computed using the earlier potential energy surface by Panda and Sathyamurthy [J. Phys. Chem. A 107, 7125 (2003)] that additionally accounts for the proton-exchange reaction between HeH+ and He. It is shown that the exchange channel contributes nearly as much as the inelastic channel to the vibrational excitation and de-excitation processes and that the total rate constants pertaining to the purely inelastic processes are largely of the same magnitude as those obtained when both inelastic and reactive channels are included in the dynamics. The inelastic rovibrational rate coefficients involving this astrophysical cation are also found to be much larger than those obtained for anions present in similar interstellar environments. [ABSTRACT FROM AUTHOR]

Two different ab initio potential energy surfaces are employed to investigate the efficiency of the rotational excitation channels for the polar molecular ion HeH+ interacting with He atoms. We further use them to investigate the quantum dynamics of both the proton-exchange reaction and the purely rotational inelastic collisions over a broad range of temperatures. In current modeling studies, this cation is considered to be one of the possible cooling sources under early universe conditions after the recombination era and has recently been found to exist in the interstellar medium. The results from the present calculations are able to show the large efficiency of the state-changing channels involving rotational states of this cation. In fact, we find them to be similar in size and behavior to the inelastic and reaction rate coefficients obtained in previous studies, where H atoms were employed as projectiles. The same rotational excitation processes, occurring when free electrons are the collision partners of this cation, are also compared with the present findings. The relative importance of the reactive, proton-exchange channel and the purely inelastic channels is also analyzed and discussed. The rotational de-excitation processes are also investigated for the cooling kinetics of the present cation under cold trap conditions with He as the buffer gas. The implications of the present results for setting up more comprehensive numerical models to describe the chemical evolution networks in different environments are briefly discussed. [ABSTRACT FROM AUTHOR]

The anion C5N− is one of the largest linear (C,N)-bearing chains detected in the interstellar medium. Here we present and discuss the general features of new ab initio potential energy surfaces describing the interaction of this linear anion with He and H2. We employ a Legendre Polynomials expansion representation for the former and an artificial neural network fit for the latter. We then carry out quantum scattering calculations to yield rotationally inelastic cross-sections for collisions with He and H2, using relative translational energy values in the range of 0.1–300 cm−1. We then obtained the corresponding inelastic rate coefficients as a function of temperature covering the range from 1 to 100 K. The results for these two systems are compared with each other, as well as with the earlier results on the C3N− colliding with the same partners. We found that the final inelastic rate coefficients for this anion are all fairly large, those from collisions with H2 being the largest. The consequences of such findings on their non-equilibrium rotational populations in interstellar environments are discussed in our conclusions. [ABSTRACT FROM AUTHOR]

The scattering cross-sections and corresponding rate coefficients for rotationally inelastic collisions of 12 C 2 − ( 2 Σ g + ) with H 2 ( 1 Σ g + ) are presented over a broad range of cold-trap temperatures. They have been calculated using quantum scattering theory that employs a new ab initio potential energy surface. The rate coefficients for the inelastic processes in the anionic partner are used to model the thermalisation dynamics of 12 C 2 − using H 2 as a buffer gas, a trap partner which is found here to be far more efficient than the typical buffer gas He and even more so than when using Ar as a partner gas. The microscopic physics underlying these findings is discussed in some detail. We additionally compute and discuss 12 C 2 − quadrupole transitions by spontaneous emission and use the newly computed rates to show that the anion's rotational levels should be in local thermal equilibrium at typical interstellar conditions. [ABSTRACT FROM AUTHOR]

The anions C |$_7$| N |$^-$| and C |$_{10}$| H |$^-$| are the two longest of the linear (C,N)-bearing and (C,H)-bearing chains that have so far been detected in the interstellar medium (ISM). In order to glean information on their collision-induced rotational state-changing processes, we analyse the general features of new ab initio potentials describing the interaction of both linear anions with H |$_2$|⁠ , one of the most abundant partners in their ISM environment. We employ an artificial neural network fit of the reduced-dimensionality potential energy surface for C |$_7$| N |$^-$|⁠...H |$_2$| interaction and discuss in detail the spatial features in terms of multipolar radial coefficients. For the C |$_{10}$| H |$^-$|⁠...H |$_2$| interaction, we use the initial grid of two-dimensional raw points to generate by quadrature the Legendre expansion directly, further including the long-range terms as discussed in the main text. Quantum scattering calculations are employed to obtain rotationally inelastic cross-sections, for collision energies in the range of 10 |$^{-4}$| to 400 cm |$^{-1}$|⁠. From them we generate the corresponding inelastic rate coefficients as a function of temperature covering the range from 10 to 50 K. The results for the rate coefficients for the longest cyanopolyyne are compared with the earlier results obtained for the smaller terms of the same series, also in collision with H |$_2$|⁠. We obtain that the inelastic rate coefficients for the long linear anions are all fairly large compared with the earlier systems. The consequences of such findings on their non-equilibrium rotational populations in interstellar environments are illustrated in our conclusions. [ABSTRACT FROM AUTHOR]

A new three-dimensional potential energy surface (PES), which describes the interaction between the OH-(X 1Σ+) anionic molecule and the Rb(2S) atomic gas has been obtained by using a highly correlated ab initio model of the electronic structure and a large atomic basis set supplemented with a set of midbond Gaussian functions. This accurate PES is being employed to evaluate the OH-(X 1Σ+) vibrational quenching efficiency induced by collisions with Rb(2S) at low and ultralow energies. Calculations employ the coupled-channel ansatz to describe the nuclear quantum dynamics and finally show a very marked dependence of the inelastic cross sections and rates, at vanishing collision energies, on the initial vibrational energy content of the partner molecules. The present findings allow us to make specific suggestions on the likely outcomes from energy interplay between the title species within a mixed MOT/Paul Trap environment. [ABSTRACT FROM AUTHOR]

We present post Hartree-Fock calculations of the potential energy surfaces (PESs) for the ground electronic states of the three alkali dimer ions Li2+, Na2+, and K2+ interacting with neutral helium. The calculations were carried out for the frozen molecular equilibrium geometries and for an extensive range of the remaining two Jacobi coordinates, R and θ, for which a total of about 1000 points is generated for each surface. The corresponding raw data were then fitted numerically to produce analytic expressions for the three PESs, which were in turn employed to evaluate the bound states of the three trimers for their J=0 configurations: The final spatial features of such bound states are also discussed in detail. The possible behavior of additional systems with more helium atoms surrounding the ionic dopants is gleaned from further calculations on the structural stability of aggregates with up to six He atoms. The validity of a sum-of-potential approximation to yield realistic total energies of the smaller cluster is briefly discussed vis-a-vis the results from many-body calculations. [ABSTRACT FROM AUTHOR]

One bound state for the very weakly interacting complex of H2 with one He atom is computed using a recently obtained, very accurate potential energy surface [A. I. Boothroyd and P. G. Martin, J. Chem. Phys. 119, 3187 (2003)] and employing a discrete variable representation expansion. The spatial features of this very diffused, “halo” state are analyzed and discussed for various isotopic variants of the title system. [ABSTRACT FROM AUTHOR]

One bound state for the very weakly interacting complex of H2 with one He atom is computed using a recently obtained, very accurate potential energy surface [A. I. Boothroyd and P. G. Martin, J. Chem. Phys. 119, 3187 (2003)] and employing a discrete variable representation expansion. The spatial features of this very diffused, “halo” state are analyzed and discussed for various isotopic variants of the title system. [ABSTRACT FROM AUTHOR]

A previously discussed potential energy surface for the CO molecule interacting with one Ar atom is extended to evaluate its dependence on molecular vibrations. The υ = 0〉 and the υ = 1〉 adiabatic potential energy surfaces are employed within a stochastic treatment to obtain the vibrational transition energy changes as the number of rare gas atoms around the CO molecule is increased. The present calculations yield shifts of the excitation energy for the (υ = 0 → υ = 1) transition in Ar cluster of variable size which are in fair agreement with experimental expectations for the limiting case of solid argon. The details of the preferential structuring and clustering of the adatoms around the dopant molecule are obtained from diffusion Monte Carlo calculations and are extensively analyzed. The specifics of the system behavior are discussed and a driving microscopic mechanism is suggested on the basis of the energy balance between the interaction potentials that are present in the title system. [ABSTRACT FROM AUTHOR]

We present a quantum mechanical study of the reaction F+D[sub 2] at ultracold temperatures based on the potential energy surface of Stark and Werner. The reaction cross section at low energies is controlled by the tunneling through the activation barrier, a mechanism that is favored by the long duration of the collision at those energies. Differences are found in the behavior of the reactive cross section compared to that for F+H[sub 2], due to the changed mass and zero point energy. A new feature is detected in the reaction probabilities and is attributed to a Feshbach resonance corresponding to a metastable state in the exit channel. [ABSTRACT FROM AUTHOR]

This paper discusses the calculation of the potential energy surfaces (PES) for the electronic singlet states of C2v and C∞v symmetries of a nitrogen molecule interacting with the atomic hydrogen negative ion. The behavior of such surfaces is analyzed as a function of relative orientations and also of the molecular internal coordinate. The PES’s have been obtained using an ab initio, multireference configuration interaction method (MRDCI) and the effects of correlation forces and of basis set size are analyzed in order to understand the role of electron transfer (ET) processes which are likely to take place during closer collisions between partners and which are suggested to be responsible for the vibronic coupling effects which occur during low-energy scattering. The general features of the orientational anisotropy of this interaction, of its dependence on the molecular coordinate, and of the strength of its coupling with the impinging negative ion are also analyzed and discussed. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The existing potential energy surfaces (PES) which have been previously suggested for the title system are analyzed in terms of their behavior in reproducing experimental data for some of the transport coefficients (diffusion and viscosity) and of total differential cross sections from crossed beam measurements. The insufficient anisotropy of the earliest of the surfaces is modified by carrying out a preliminary sensitivity study on the transport properties and then a further global optimization using the molecular beam data. The final potential function is found to be markedly more anisotropic in the well region and at the onset of the repulsive wall, and it is shown to reproduce very well both the existing scattering data and the available transport coefficients. The simple optimization procedure discussed here could therefore be used profitably with a broad range of van der Waals (vdW) molecular mixtures and thus allow us to improve on some initial description of their anisotropic interactions by means of direct computational comparisons with existing scattering data. © 1994 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Full quantum calculations of several transport and relaxation cross sections have been carried out for the title system, using the multiproperty potential energy surface obtained earlier by Gianturco et al. [Chem. Phys. 109, 417 (1986)] which has been recently shown to be one of the most reliable descriptions of the He–N2 interaction. A rigorous close coupling (CC) treatment of the scattering problem turns out to be the only realistic choice for evaluating viscomagnetic relaxation data and for anisotropy-dependent nonequilibrium properties. A comparison of the present calculations with classical trajectory (CT) estimates is carried out for several transport cross sections as function of both the collision energy and the temperature of the mixture. It is clearly shown by the present results that classical treatments markedly differ from the quantum calculations at collision energies which are comparable with the average well depth of the chosen interaction. On the other hand, CT and CC values are nearly coincident at higher collision energies for all the computed properties. Thus, their combined use in evaluating the temperature dependence of diffusion and viscosity coefficients reveals the high quality of the present multiproperty interaction vis a vis the experimental findings examined in this work. [ABSTRACT FROM AUTHOR]

The usual kinetic theory of dilute gaseous mixtures is employed, via the infinite-order sudden (IOS) decoupling scheme for the dynamics, to obtain generalized collision integrals and transport properties for molecular mixtures containing N2 and various rare gases (He, Ne, and Ar). The relevant interaction potentials originate from a previous study [F. A. Gianturco, M. Venanzi, and A. S. Dickinson, Mol. Phys. 65, 563 (1988)] of the above systems in which a multiproperty analysis of their quality and reliability was attempted by combining scattering data, when available, with diffusion coefficients and interaction viscosity data to select the most accurate of the potential energy surfaces (PES) at hand. The extension of the calculations to second-order effects allows us to test the importance of such corrections on diffusion and viscosity coefficients, to follow their dependence on the mole fraction of the mixtures, to obtain thermal diffusion and thermal conductivity results and to futher assess the feasibility of multiproperty tests of simple atom–diatom interactions via the calculation of a broader range of transport coefficients. [ABSTRACT FROM AUTHOR]

A full quantum study of the fragmentation dynamics for argon trimer ions is carried out using a previously computed potential energy surface (PES). The initial and final internal states which are being considered are the bending–stretching states of the trimer and the rotovibrational states of the residual dimer ion. The treatment employs the helicity decoupling approximation over a broad range of total angular momentum values (J) and analyses the final distribution of rotational–vibrational states as a function of the metastable states of the J values and of the ‘‘tumbling’’ (helicity) quantum number Ω. It is found that at least two different effects, one mainly dynamically related to the centrifugal barrier and another to the orientational nature of the coupling potential field, can be discerned to explain the fragmentation results. [ABSTRACT FROM AUTHOR]

The quantal IOS approximation in here employed to study interference structures in the rotationally inelastic, state-to-state differential cross sections for polar diatomic targets (LiH, FH, and CO) interacting with He atoms. Quite realistic expressions are used to describe the relevant potential energy surfaces (PES) which were taken from previous works that tested them against accurate experimental findings for total and partial differential cross sections. Specific features like short-range anisotropy and well depth, long-range attractive regions and overall range of action for each potential employed are analyzed and discussed in relation to their influence on rotational rainbows appearance and on the possible observation of cross section extrema in rotational energy distributions. [ABSTRACT FROM AUTHOR]

In this paper we extend our previous study (F. Schneider, F. Di Giacomo, and F. A. Gianturco, J. Chem. Phys. 104, 5153) on the topology of the electronic states of the neutral H2O molecule in C2v symmetry by examining the lowest ten potential energy surfaces of the water molecular cation in its doublet states. The relevant electronic energy surfaces of H2O+ are shown as 2D contour maps where possible reaction pathways for several low-lying potential energy surfaces of H2O+ are clearly seen and therefore can be discussed and analyzed in some detail. The present results were obtained using ab initio multireference configuration interaction calculations at 184 nuclear arrangements, as described in our previous paper dealing with the neutral H2O. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present here computational results on 15 C2v potential energy surfaces (PES) of H2O in its singlet state, while further results on the doublet state of the cation of the same system will be reported in a following paper. The PES are shown as 2D contour maps. Reaction pathways for symmetric dissociation of H2O and photoionisation spectra of H2O are discussed and analyzed in some detail. The results were obtained using ab initio multireference configuration interaction (MRDCI) calculations at 184 nuclear arrangements and should provide one of the most extensive analysis of the electronic features of this very important chemical system. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Extensive ab initio configuration interaction calculations have been carried out for different directions of approach of a proton to a rigid acetylene molecule. The calculated potential energy curves of several singlet states are presented. The anisotropy we found allows us to explain features of the charge transfer mechanism during proton–acetylene collisions as observed in recent molecular beam experiments. An important theoretical conclusion is the preference of the linear approach of protons in collisions with acetylene for the formation of acetylene ions. [ABSTRACT FROM AUTHOR]

This paper analyses in detail the energy redistribution from the upper vibrational levels of Cs dimers, thought to be obtained from initial recombination processes that generate excited internal states of the triplet configuration Σ. Their quenching is examined as they are made to further collide with He buffer gas at temperatures below and around 100 mK. The relevant cross sections are computed by using a multichannel quantum dynamical approach and employ a full, ab initio potential energy surface. Due to their smallness (see Ref. [R.B. Ross, J.M. Powers, T. Atashroo, W.C. Ermler, I.A. LaJohn, P. Christiansen, J. Chem. Phys. 93, 6654 (1999)]) the fine structure effects have not been explicitly included in this study. The final, cumulative cross-sections are discussed and analyzed in terms of the overall quenching behavior shown by different initial states of the dimer and in terms of the changing ratios between collisional cooling and vibrational quenching cross sections as a function of trap temperature. The corresponding quenching rates are also computed and analysed. [ABSTRACT FROM AUTHOR]

The quantum dynamics of the rotational quenching of the 24MgH+(X 1Σ+) molecular cation interacting with 4He(1S) as a buffer gas, at relative temperatures ranging from 1 K down to millikelvins, is described by accurate close coupling scattering calculations on an ab initio potential energy surface. The efficiency of the process is quantitatively analyzed by employing the ab initio quenching rates and cross sections and effective decay rate values are obtained from simple unimolecular kinetics over a broad range of trap conditions. [ABSTRACT FROM AUTHOR]

In the present computational study we discuss the behavior of the MgH+(X1Σ+) molecular ion interacting with Rb(2S) and argue that it constitutes an amenable system for ultracold chemistry studies in a Coulomb crystal environment. In particular, we find from our calculations that there is a number of different ways in which this system can chemically evolve and we present results from a diabatic representation of the potential energy surfaces (PESs) of the electronic states which are relevant for the realistic description of an experimental setup in which a cloud of ultracold laser-cooled Rb atoms is superimposed onto a Coulomb crystal arrangement of MgH+ molecular ions. Our findings suggest the most likely pathways for either the formation of a new Coulomb crystal of Rb ions or the combination of cold Mg+, MgH+ and Rb+ mixtures within the trap under consideration. [ABSTRACT FROM AUTHOR]

A newly computed potential energy surface, which describes the forces at play between the OH− ( X 1Σ+) anionic molecule (treated as a rigid rotor at its equilibrium geometry) and the Rb(2S) atomic gas was obtained from fully ab initio methods, yielding highly correlated electronic wavefunctions for the interacting partners. It is in turn employed to calculate their rotationally quenching collision cross sections at ultralow energies and for different initial rotational states of the molecular anion. The results suggest that these strongly interacting partners are among the most efficient systems in providing very large internal de-excitation rates whenever the collision regime of an ultracold trap can occur for the partners. The collision encounters at such vanishing values of translational energies are seen to be strongly controlled by the behaviour of the real part of the scattering length as a function of the initial rotational state: the latter indicates, in fact, the presence of several virtual states close to the dissociation threshold of the complex. [ABSTRACT FROM AUTHOR]

The electronic structures of the manifold of potential energy surfaces generated in the lower energy range by the interaction of the MgH+(X1Σ+) cationic molecule with Rb(2S) neutral atom are obtained over a broad range of Jacobi coordinates from strongly correlated ab initio calculations which use a Multireference (MR) wavefunction within a Complete Active Space (CAS) approach. The relative features of the lowest five surfaces are analyzed in terms of possible collisional outcomes when employed to model the ultracold dynamics of ionic molecular partners. [ABSTRACT FROM AUTHOR]

An ab initio computed potential energy surface is employed to evaluate the interaction of the OH+(3Σ -) molecule with 4He(1S) atom and an analytic fitting of the raw points is directly employed in quantum scattering calculations at ultralow collision energies. The Hund's case (b) chosen to handle the spin-rotation coupling allows to extract from the numerous inelastic cross sections the relative importance of pure “spin flip" vis-à- vis rotational cooling cross sections. The final rates of all the above processes as a function of the initial |N〉 state are analysed in detail and possible propensity rules are discussed. [ABSTRACT FROM AUTHOR]

The structural features of a varying number of pH2 molecules bound to one dopant molecule of OCS are examined using quantum calculations with the Diffusion Monte Carlo (DMC) approach. The interaction forces were obtained from ab initio calculations for the OCS–pH2 system and for the pH2 dimer. The overall potential energy surface is then constructed as a sum of interpartner potentials where the pH2 molecules are treated as spherical species. The calculations suggest that pH2 molecules indeed behave as a quantum solvent and that an initial “doughnut” of five to six equivalent pH2 partners is formed on the bisecting middle plane perpendicular to the OCS main axis, showing there strong spatial delocalization. Further added molecules move sequentially to either end of the dopant species, a process seen here to be increasingly more affected by the H2–H2 interactions contributing to clusters stability. [ABSTRACT FROM AUTHOR]

The potential energy surface (PES) describing the interactions between and 4   He and an extensive study of the energies and structures of a set of small clusters, Li 2 (He) n , were reported in a previous series of publications. In the present work, the same analysis is extended to the case of the excited and of the ionized Li moiety. Calculated interaction potentials for the two title systems and the corresponding fitting of the computed points are shown. For both surfaces the MP4 method with cc-pV5Z basis sets has been used to generate an extensive range of radial/angular coordinates of the two-dimensional PESs which describe rigid rotor molecular dopants interacting with one He partner. [ABSTRACT FROM AUTHOR]

The full dimensional potential energy surface for the He-CO complex, V (R, θ, r[sub CO]), has been calculated using a recently developed scheme which combines density functional theory with the long range dispersion contributions obtained from perturbative theory. Then the two adiabatic surfaces obtained by the integration of the full potential over the vibrational coordinate of CO have been used to calculate the bound states of the van der Waals complex for both v[sub CO] = 0 and v[sub CO] = 1. Calculations of the wavefunctions and of the frequencies of various rotational and rovibrational transitions is seen to provide good overall agreement with the available experiments on the title system. [ABSTRACT FROM AUTHOR]

New measurements for the thermal diffusion factor and for the diffusion coefficient derived from it are reported for the Ar-CO2 gaseous mixture at different temperatures and for various concentrations of the CO2 molecule. Several of the interaction potentials between the partners which have been suggested in the literature are examined, and quantum dynamics calculations are carried out to compare their performances using the infinite order sudden dynamic decoupling scheme. The present results are compared with other experiments and show clearly that, although one of the empirical potentials turns out to be the most realistic for describing such properties, a unique form of a multiproperty-tested potential energy surface for this system is still lacking. [ABSTRACT FROM AUTHOR]

The full three-variable potential-energy surface for the Ar-CO complex, V(R,θ,r[sub CO]), has been calculated using a recently developed scheme which combines density-functional theory (DFT) with the long-range dispersion contributions obtained from perturbation theory. The two adiabatic surfaces given by integration of the full potential over the vibrational coordinate of CO have been then used to calculate the bound states of the van der Waals complex for both v[sub CO]=0 and v[sub CO]=1. Calculations of the wave functions and of the frequencies of various rotational and rovibrational transitions provide overall good agreement both with the experiments and with the results obtained using the most recent, and more computationally demanding, potential-energy surfaces for the title system. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The anion C5N− is one of the largest linear (C,N)-bearing chains detected in the interstellar medium. Here we present and discuss the general features of new ab initio potential energy surfaces describing the interaction of this linear anion with He and H2. We employ a Legendre Polynomials expansion representation for the former and an artificial neural network fit for the latter. We then carry out quantum scattering calculations to yield rotationally inelastic cross-sections for collisions with He and H2, using relative translational energy values in the range of 0.1–300 cm−1. We then obtained the corresponding inelastic rate coefficients as a function of temperature covering the range from 1 to 100 K. The results for these two systems are compared with each other, as well as with the earlier results on the C3N− colliding with the same partners. We found that the final inelastic rate coefficients for this anion are all fairly large, those from collisions with H2 being the largest. The consequences of such findings on their non-equilibrium rotational populations in interstellar environments are discussed in our conclusions. [ABSTRACT FROM AUTHOR]