Papers by Keshav Kumar Singh
Astrophysics and Space Science, 2018
Ethanimine (CH 3 CHNH) is an important prebiotic molecule since it is a precursor of amino acid α... more Ethanimine (CH 3 CHNH) is an important prebiotic molecule since it is a precursor of amino acid α-alanine in Strecker synthesis. Two isomers (E and Z) of ethanimine were detected in the molecular cloud Sagittarius B2 north during GBT-PRIMOS survey. A possible radical-molecule reaction pathway has been proposed for the formation of ethanimine in the interstellar medium (ISM) from some previously detected interstellar molecules like methylene (both triplet CH 2 (3 B 1) and singlet CH 2 (1 A 1)) and methyenimine (CH 2 NH). The mechanism has been studied in the gas phase and in water ice with the help of density functional theory at B2PLYPD/6-311++G (2d, p) level of theory. It is observed that E-ethanimine forms efficiently in gas phase but ice reactions are favorable only in the hot core of molecular clouds. Same is true for the formation of Z-ethanimine which forms only at the surface of water cluster as the height of entrance barrier for formation of Z-ethanimine is similar to that of Eethanimine. Isomerization from E to Z form is also studied and found to be forbidden due to large entrance barrier. Out of the two reaction system CH 2 (3 B 1) + CH 2 NH and CH 2 (1 A 1) + CH 2 NH, later is more favorable then the former one due to the small entrance barrier. Still, much of the detected abundance of ethanimine comes from the reaction of CH 2 (3 B 1) with CH 2 NH as since CH 2 (1 A 1) has very low abundance compared to the CH 2 (3 B 1) in ISM. The proposed pathway seems to be a promising candidate for the ethanimine formation in ISM.
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Papers by Keshav Kumar Singh