Astronomical identification of CN^-, the smallest observed molecular anion

  title={Astronomical identification of CN^-, the smallest observed molecular anion},
  author={M. Ag{\'u}ndez and J. Cernicharo and M. Gu{\'e}lin and C. Kahane and E. Roueff and J. Kłos and F. J. Aoiz and F. Lique and N. Marcelino and J. Goicoechea and M. Garcia and C. Gottlieb and M. McCarthy and P. Thaddeus},
We present the first astronomical detection of a diatomic negative ion, the cyanide anion CN-, as well as quantum mechanical calculations of the excitation of this anion through collisions with para-H2. CN- is identified through the observation of the J = 2-1 and J = 3-2 rotational transitions in the C-star envelope IRC +10216 with the IRAM 30-m telescope. The U-shaped line profiles indicate that CN-, like the large anion C6H-, is formed in the outer regions of the envelope. Chemical and… Expand

Figures and Tables from this paper

Rotational excitation of C2H− anion in collision with H2
The discovery of anions in the interstellar medium has shown that they are very reactive species. This gave them great importance in the modeling of the chemical and astrophysical evolution of theExpand
The rotational spectrum of the negative molecular ion NCO– has been observed both in a supersonic molecular beam and in a low-pressure glow discharge. The identification is ironclad because of theExpand
First rate coefficients for an interstellar anion: application to the CN−–H2 collisional system
Recently, several molecular anions have been detected in the interstellar medium. Accurate modelling of their microwave emission spectra requires the calculation of rates for rotational excitationsExpand
Detectable interstellar anions: Examining the key factors.
The high eAEs and the large dipole moment of most of the neutral species suggest a high detectability of their corresponding anions in the interstellar medium if they are abundant. Expand
Direct observation of long-lived cyanide anions in superexcited states
The cyanide anion (CN − ) has been identified in cometary coma, interstellar medium, planetary atmosphere and circumstellar envelopes, but its origin and abundance are still disputed. An isolated CNExpand
Threshold photodetachment spectroscopy of the astrochemical anion CN.
Threshold photodetachment spectroscopy on the molecular anion CN- shows a typical energy dependence of the detachment cross section yielding a determination of the electron affinity of CN to greater precision than has previously been known at 31 163(16) cm-1. Expand
The Cation, Anion, and Radical Isomers of C4H4N :Computational Characterization and Implications for Astrophysical and Planetary Environments.
By characterizing C4H4N isomers, anionic, radical, and cationic structures that may be present in Titan's atmosphere and dark molecular clouds are identified and select formation pathways to these structures from Titan's existing or postulated gas-phase species are discussed. Expand
A high-resolution photoelectron imaging and theoretical study of CP- and C2P.
The current study suggests that the combination of high-resolution photoelectron imaging and quantum chemistry can be used to determine accurate molecular constants for exotic radical species of astronomical interest. Expand
Bound and continuum-embedded states of cyanopolyyne anions.
This work investigates the bound and continuum states of four cyanopolyyne anions, CN-, C3N-, C5N-, and C7N-, by means of equation-of-motion coupled-cluster method augmented with complex absorbing potential and predicts that already in CN-, the smallest anion in the family, there are several low-lying metastable states of both singlet and triplet spin symmetry. Expand
Discovery of Interstellar Anions in Cepheus and Auriga
We report the detection of microwave emission lines from the hydrocarbon anion C6H– and its parent neutral C6H in the star-forming region L1251A (in Cepheus), and the pre-stellar core L1512 (inExpand


The rotational spectrum of CN-.
The rotational spectrum of the molecular negative ion CN(-) has been detected in the laboratory at high resolution by well-resolved nitrogen quadrupole hyperfine structure in the lowest rotational transition, and a measurable Doppler shift owing to ion drift in the positive column of the discharge. Expand
Laboratory and Astronomical Identification of the Negative Molecular Ion C6H
The negative molecular ion C6H- has been detected in the radio band in the laboratory and has been identified in the molecular envelope of IRC +10216 and in the dense molecular cloud TMC-1. TheExpand
Calculations on the Formation Rates and Mechanisms for CnH Anions in Interstellar and Circumstellar Media
The rate coefficients for the radiative attachment reactions between the radicals CnH ( -->n = 2?8) and electrons have been calculated with the aid of quantum chemistry using a phase-space theory inExpand
Astronomical detection of C 4 H , the second interstellar anion
Aims. Following the recent detection of C6H − in the laboratory and in space we have succeeded in studying the microwave spectrum of C4H − . We report here the first detection in space of thisExpand
Quantum-chemical investigations of small molecular anions
Abstract Dedicated to Dr Gerhard Herzberg on the occasion of his 90th birthday Recent large-scale ab initio calculations for small negative molecular ions are reviewed. Accurate equilibriumExpand
Laboratory detection of the negative molecular ion CCH
Aims. This paper reports the laboratory detection of the rotational spectrum of the acetylide anion, CCH - . Methods. Five successive rotational transitions have been measured to high accuracy in aExpand
Hydrocarbon Anions in Interstellar Clouds and Circumstellar Envelopes
The recent detection of the hydrocarbon anion C6H- in the interstellar medium has led us to investigate the synthesis of hydrocarbon anions in a variety of interstellar and circumstellarExpand
Reactions of H, N, and O atoms with carbon chain anions of interstellar interest : An experimental study
The molecular ions HC and HC have recently been identified both in the laboratory and in astronomical environments. In addition, carbon chain anions have been proposed as potential carriers of theExpand
Laboratory and Astronomical Detection of the Negative Molecular Ion C3N
The negative molecular ion C3N− has been detected at millimeter wavelengths in a low-pressure laboratory discharge, and then with frequencies derived from the laboratory data in the molecularExpand
Detection of the carbon chain negative ion C8H- in TMC-1
The negative molecular ion C8H- has been detected in the Galactic molecular source TMC-1. Four rotational transitions have been observed in the centimeter-wave band with the NRAO 100 m Green BankExpand