Related papers: Molecular anions in circumstellar envelopes, inter…
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 circumstellar environments. We find that the anion/neutral…
Results are presented from a survey for molecular anions in seven nearby Galactic star-forming cores and molecular clouds. The hydrocarbon anion C6H- is detected in all seven target sources, including four sources where no anions have been…
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…
We report new observations of molecular anions with the Yebes 40m and IRAM 30m telescopes toward the cold dense clouds TMC-1 CP, Lupus-1A, L1527, L483, L1495B, and L1544. We detected for the first time C3N- and C5N- in Lupus-1A and C4H- and…
Low-energy cosmic rays are a fundamental source of ionization for molecular clouds, influencing their chemical, thermal and dynamical evolution. The purpose of this work is to explore the possibility that a low-energy component of…
(abridged) The fairly recent detection of a variety of anions in the Interstellar Molecular Clouds have underlined the importance of realistically modeling the processes governing their abundance. To this aim, our earlier calculations for…
Positive ions play a fundamental role in the interstellar chemistry, especially in cold environments where chemistry is believed to be mainly ion-driven. However, in contrast with neutral species, most of the cations present in the…
This paper deals with the possible formation of two molecular anions often considered likely components in the physical environments of the Interstellar Medium ( ISM) : $\mathrm{C_2H^-}$ and $\mathrm{NCO^-}$. They are both discussed here by…
The low-mass protostellar region L1527 is unusual because it contains observable abundances of unsaturated carbon-chain molecules including CnH radicals, H2Cn carbenes, cyanopolyynes, and the negative ions C4H- and C6H-, all of which are…
We study the formation of first molecules, negative Hydrogen ions and molecular ions in model of the Universe with cosmological constant and cold dark matter. The cosmological recombination is described in the framework of modified model of…
We have investigated the role of molecular anion chemistry in pseudo-time dependent chemical models of dark clouds. With oxygen-rich elemental abundances, the addition of anions results in a slight improvement in the overall agreement…
Astronomical evolution mechanism of small size polycyclic aromatic hydrocarbon (PAH) was analyzed using the first principles quantum-chemical calculation. Starting model molecule was benzene (C6H6), which would be transformed to (C5H5) due…
Long-chain hydrocarbon anions CnH- (n=4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models…
The field of astrochemistry has seen major advances triggered by the completion of new powerful radio telescopes, with gains in sensitivity of receivers and in bandwidth. To date, about 330 molecular species are detected, in interstellar…
Studying chemical reactions at very low temperatures is of importance for the understanding of fundamental physical and chemical processes. At very low energies, collisions are dominated by only a few partial waves. Thus, studies in this…
The formation of anionic species in the interstellar medium from interaction of linear molecules containing carbon, nitrogen and hydrogen as atomic components (polyynes) with free electrons in the environment is modelled via a quantum…
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 (in Auriga). The carbon-chain-bearing species C4H,…
A first-principle theoretical approach to study the process of radiative electron attachment is developed and applied to the negative molecular ions CN$^-$, C$_4$H$^-$, and C$_2$H$^-$. Among these anions, the first two have already been…
The transition between atomic and molecular hydrogen is associated with important changes in the structure of interstellar clouds, and marks the beginning of interstellar chemistry. Because of the relatively simple networks controlling…
We demonstrate that the formation of negative hydrogen ions (H-) occurs in a wide class of atomic and molecular collisions. In our experiments, H- emission from hydroxyl cations and acetone molecules was observed in keV-energy collisions.…