Elementary Reactions and Their Role in Gas-Phase Prebiotic Chemistry

Abstract

Abstract:The formation of complex organic molecules in a reactor filled with gaseous mixtures possibly reproducing the primitive terrestrial atmosphere and ocean demonstrated more than 50 years ago that inorganic synthesis of prebiotic molecules is possible, provided that some form of energy is provided to the system. After that groundbreaking experiment, gas-phase prebiotic molecules have been observed in a wide variety of extraterrestrial objects (including interstellar clouds, comets and planetary atmospheres) where the physical conditions vary widely. A thorough characterization of the chemical evolution of those objects relies on a multi-disciplinary approach: 1) observations allow us to identify the molecules and their number densities as they are nowadays; 2) the chemistry which lies behind their formation starting from atoms and simple molecules is accounted for by complex reaction networks; 3) for a realistic modeling of such networks, a number of experimental parameters are needed and, therefore, the relevant molecular processes should be fully characterized in laboratory experiments. A survey of the available literature reveals, however, that much information is still lacking if it is true that only a small percentage of the elementary reactions considered in the models have been characterized in laboratory experiments. New experimental approaches to characterize the relevant elementary reactions in laboratory are presented and the implications of the results are discussed.

On the intrinsic photophysics of indigo: a time-resolved photoelectron spectroscopy study of the indigo carmine dianion

“…2), leading to direct detachment to the D0. In pump-probe experiments, a pump at 2.21 eV or 2.33 eV was used while a probe at 3.1 eV was employed to detach 5 from the S1 state.…”

“…The two beams were combined collinearly using a dichroic mirror before intersecting the ion packet in the interaction region. The cross correlation of the two pulses was around 130 fs, determined in a thin BBO crystal or by above-threshold photodetachment of 5 iodide. Nanosecond pulses were produced from an optical parametric oscillator (Panther Ex, Continuum), pumped by the 3 rd harmonic of an Nd:YAG laser at 10 Hz.…”

“…In general, photo-resistive chromophores are a topic of great interest and have, for example, been linked with the survival of primordial organisms on early Earth. [3][4][5] The photoresistive properties are related to the excited state dynamics of the chromophore and here we present a direct study of the S 1 35 dynamics of a disulfonated derivative, indigo carmine (InC 2-, Fig. 1(b)), using time-resolved photoelectron spectroscopy.…”

On the Participation of Photoinduced N–H Bond Fission in Aqueous Adenine at 266 and 220 nm: A Combined Ultrafast Transient Electronic and Vibrational Absorption Spectroscopy Study

“…One central factor, which has been postulated to contribute to this selection process on the early pre-biotic Earth, [1][2][3] is the resistance that the nucleobases exhibit toward photo-chemical damage following the absorption of solar UV radiation. [4][5][6] As such, the DNA and RNA nucleobases are classed as photostable species.…”

Dimerization of methanimine and its charged species in the atmosphere of Titan and interstellar/cometary ice analogs

“…Methanimine, CH 2 =NH, is alleged to be an important species in prebiotic chemistry since it is a possible precursor of the simplest amino acid, glycine, via its subsequent reactions with HCN and H 2 O (Balucani 2009(Balucani , 2012Woon 2002), and it is an essential intermediate in the Strecker synthesis of aminoacetonitrile (Danger et al 2011) and glycine (Rimola et al 2010;Ugliengo et al 2011;He & Smith 2014;Holtom et al 2005;Arnaud et al 2000). Methanimine was observed a long time ago in the interstellar medium (Godfrey et al 1973).…”