Formation of Negative Ions upon Dissociative Electron Attachment to the Astrochemically Relevant Molecule Aminoacetonitrile

Abstract

Aminoacetonitrile (NH2CH2CN, AAN) is a molecule relevant for interstellar chemistry and the chemical evolution of life. It is a very important molecule in the Strecker diagram explaining the formation of amino acids. In the present investigation, dissociative electron attachment to NH2CN was studied in a crossed electron-molecular beams experiment in the electron energy range from about 0 to 17 eV. In this electron energy range, the following six anionic species were detected: C2H3N2(-), C2H2N2(-), C2H2N(-), C2HN(-), CN(-), and NH2(-). Possible reaction channels for all the measured negative ions are discussed, and the experimental results are compared with calculated thermochemical thresholds of the observed anions. Similar to other nitrile and aminonitrile compounds, the main anions detected were the negatively charged nitrile group, the dehydrogenated parent molecule, and the amino group. No parent anion was observed. Low anion yields were observed indicating that AAN is less prone to electron capture. Therefore, AAN can be considered to exhibit a relatively long lifetime under typical conditions in outer space.

Dissociation of methyl formate (HCOOCH3) molecules upon low-energy electron attachment

“…For example, abundant ion yield of the dehydrogenated parent anion was previously observed in DEA to organic acids and glycolaldehyde (Sailer et al 2003;Ptasińska et al 2005b;Pelc et al 2002Pelc et al , 2004Pelc et al , 2005, nitriles (Tanzer et al 2015;Pelc et al 2016), nitrocompounds (Pelc et al 2007) and biomolecules (Denifl et al 2008;Vizcaino et al 2012). As the hydrogen atom could be abstracted from two sites in the methyl formate molecule, the C 2 H 3 O − 2 anion may be formed via two DEA channels.…”

Reactions in the Radiosensitizer Misonidazole Induced by Low-Energy (0–10 eV) Electrons

“…On the other hand, a large EA does not necessarily lead to a high cross section for the formation of CN − via DEA. For example, CN − formation from compounds like (amino)acetonitrile or benzonitrile [42,43,44] was comparatively weak due to the underlying decomposition mechanism. Although it is also formed for these compounds via a single C–CN bond cleavage, the dissociation mechanism was suggested to be indirect in the way that the excess electron initially resides in a π* (CN) antibonding MO and decomposition into CN − requires transfer of the available energy from CN into the C–CN coordinate (vibrational predissociation).…”

Negative ion formation and fragmentation upon dissociative electron attachment to the nicotinamide molecule

“…However, as recent studies show, the formation of NH 2 À from molecules having the NH 2 moiety is quite an efficient process. 61,62 Denitely more insight into the formation of the structure of the anion with m/z ¼ 16 was brought by studies of electron capture by the glycine molecules using high-resolution mass spectrometry. 58 These investigations showed that both types of ions, i.e., O À and NH 2 À , are formed in the interaction of low-energy electrons with glycine molecules.…”

“…The loss of one hydrogen atom is a common DEA channel leading to the formation of the (M-H) À anion, which was observed for several organic molecules. 54,[60][61][62]64 The formation of the dehydrogenated parent anion from the NA molecule is an endothermic process described by the following DEA reaction.…”

“…The CN species is oen called a pseudohalogen molecule as it possesses a huge value of EA of about 3.86 eV (Table 1), which is even higher than the EA of the halogen atoms. The CN À anion was detected in several studies of electron attachment to the nitrile, 62,65 One detailed pathway leading to CN À generation is presented in Fig. 4.…”