Gas-Phase Reactions in Extraterrestrial Environments: Laboratory Investigations by Crossed Molecular Beams

Abstract

We have investigated gas-phase reactions of N((2)D) with the most abundant hydrocarbons in the atmosphere of Titan by the crossed molecular beam technique. In all cases, molecular products containing a novel CN bond are formed, thus suggesting possible routes of formation of gas-phase nitriles in the atmosphere of Titan and primordial Earth. The same approach has been recently extended to the study of radical-radical reactions, such as the reaction of atomic oxygen with the CH(3) and C(3)H(5) radicals. Products other than those already considered in the modeling of planetary atmospheres and interstellar medium have been identified.

Formation of nitriles and imines in the atmosphere of Titan: combined crossed-beam and theoretical studies on the reaction dynamics of excited nitrogen atoms N(2D) with ethane

“…Therefore, the simplest amino acid can be formed starting from simple molecules relatively abundant in extraterrestrial environments, such as the interstellar medium and, possibly, primitive Earth. 30,57 In conclusion, the chemistry that controls the formation of N-containing organic compounds in the atmosphere of Titan, as well as that of other bodies where both molecular nitrogen and hydrocarbons are present, is slowly being unveiled. Much information, however, is still missing on many processes responsible for the nitriles/imines budget.…”

Combined Crossed Molecular Beam and Theoretical Studies of the N(2D) + CH4 Reaction and Implications for Atmospheric Models of Titan

“…Although kinetic studies are available , and reaction mechanisms have been speculated from rate constants, a better knowledge of the reactive behavior of atomic nitrogen requires an investigation at the level of reaction dynamics. The capability achieved in our laboratory to generate intense continuous supersonic beams of atomic nitrogen has opened up the possibility of studying the reactive scattering of this species in crossed molecular beam (CMB) experiments with mass-spectrometric (MS) detection. − …”

“…In recent years, we have investigated − several reactions of N atoms in their first excited metastable state, 2 D 5/2,3/2 (energy content: 230.0 kJ/mol; radiative lifetimes of 2 D 3/2 and 2 D 5/2 are 6.1 × 10 4 and 1.4 × 10 5 s, respectively). Notwithstanding its high energy content, the metastable character of N( 2 D) and the much larger rate constants of its reactions with respect to those of N( 4 S) , (especially when the reactive partner is a closed-shell molecule) suggest a potential role of this species in the above-mentioned chemical environments, similarly to the case of O( 1 D) as opposed to O( 3 P).…”

Low-Temperature Branching Ratios for the Reaction of State-Prepared N2+with Acetonitrile

“…Gaussian functions, and the product BRs were calculated after baseline subtraction and correction for the 13 C contribution.…”

“…It is interesting to note that the routes leading to the formation of CH 3 CN in Titan’s atmosphere were not clearly known for a long time owing to limited experimental data. As a result, the possible reaction pathways leading to CH 3 CN formation were not included in many pre-Cassini models. , However, following the pioneering crossed molecular beam (CMB) work on N( 2 D) + C 2 H 4 reaction by Balucani et al, , recent models appear to accept and include the insertion of N( 2 D) into C 2 H 4 as the major route leading to the production of CH 3 CN. Balucani at al .…”