Alka Misra - Academia.edu (original) (raw)

Papers by Alka Misra

Monthly Notices of the Royal Astronomical Society, 2021

Monthly Notices of the Royal Astronomical Society, 2021

Springer Proceedings in Physics, 2019

Acetaldehyde is a well-known interstellar molecule which is important for astrochemistry as it ca... more Acetaldehyde is a well-known interstellar molecule which is important for astrochemistry as it can undergo reaction with nitrogen-containing chemical species and can form amino acids or their precursors. Quantum chemical calculations at wB97XD/6-311++G(2d,p) level of theory were performed to study its formation mechanism from the reaction between atomic carbon C(3P) and methanol adsorbed on the surface of interstellar water ice. It was observed that acetaldehyde is formed from a two-step mechanism where the first step is a barrier-mediated step which generates radicals CH3 and H–CO followed by a barrierless addition of these radicals in interstellar ice (step 2). Due to a proton relay mechanism, the entrance barrier is very small and the formation of acetaldehyde is observed to be very efficient in the interstellar ice.

Organic Chemistry Plus

N-methylformamide (NMF), E & Z containing an amide bond, a vital component of peptides, is one of... more N-methylformamide (NMF), E & Z containing an amide bond, a vital component of peptides, is one of the simplest derivatives of formamides. It is detected towards the hot molecular core of the Sgr B2(N2) molecular cloud with the Atacama Large Millimeter/submillimeter Array (ALMA). It is proposed that the radical-molecule mechanism can be used as a strong contrivance to investigate the formation of NMF in the interstellar medium (ISM) via some interstellar molecules like methylidene CH2(1Σ1 & 3Σ1) and formamide (NH2CHO). The density functional theory (DFT) at B3LYP/6-311G (d,p) has been applied to study the mechanisms. All the possible cases of E- & Z-NMF formation with singlet and triplet CH2 have been investigated. It is found that the formation of E-NMF with CH2(1Σ1) and Z-NMF with CH2(3Σ1) is more feasible and favorable in comparison to E-NMF formation from CH2(3Σ1) and Z-NMF with CH2(1Σ1).

International Journal of Astrobiology, 2020

The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectivel... more The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radi...

Journal of Molecular Structure

Research in Astronomy and Astrophysics

Monthly Notices of the Royal Astronomical Society

Astrophysics and Space Science

Origins of Life and Evolution of Biospheres

Research in Astronomy and Astrophysics

The European Physical Journal D

The long carbon chain molecules could be abundant in interstellar medium and play an important ro... more The long carbon chain molecules could be abundant in interstellar medium and play an important role in interstellar chemistry. Methylcyanodiacetylene (MCDA), member of methylcyanopolyyne CH 3 (C = C) n CN family was first detected in interstellar medium with green bank telescope (GBT) toward TMC-1. In this paper structural and vibrational spectral features of MCDA have been studied, using density functional theory (DFT) with different basis sets like and ab-initio theory (MP2) quantum chemical methods. Optimized geometry and infrared spectra have been calculated and a complete vibrational assignment based on potential energy distribution along the internal coordinates has been reported. Green Bank Telescope (GBT) toward the Taurus molec

Radical-radical and radical-neutral interaction schemes are very important for the formation of c... more Radical-radical and radical-neutral interaction schemes are very important for the formation of comparatively complex molecules in low temperature chemistry. An attempt has been made to explore the possibility of formation of complex organic molecules in interstellar medium, through detected interstellar molecules like CH 3 CN and HCOOH. The gas phase reactions were theoretically studied using quantum chemical techniques. We employed the density functional theory (DFT) at the B3LYP/6-311G (d,p) level. The reaction energies, potential barrier and optimized structures of all the geometries, involved in the reaction path, has been discussed. We report the potential energy sufaces for the reactions considered in this work.

E- Cyanomethamine is a newly detected molecules in Sgr B2(N) in 2013. E-Cyanomethanimine, HNCHCN,... more E- Cyanomethamine is a newly detected molecules in Sgr B2(N) in 2013. E-Cyanomethanimine, HNCHCN, is a slightly unsaturated sibling of aminoacetonitrile, H2NCH2CN. The detection of interstellar E-cyanomethanimine (E-HNCHCN), toward Sgr B2 (N) in a publicly available GBT spectral survey has been made using a reaction product screening method. In view of significance of the molecule C2N2H2 in reactions leading to the formation of adenine, which is one of four nucleobases that form the "rungs" seen on the double-helix, ladder-like structure of DNA, an attempt has been made in the present quantum chemical study to understand the reaction mechanism involving hydrogen and NCCN molecule that may lead to the formation of E-cyanomethamine in interstellar molecular clouds.The synthesis of the molecule is reported to be difficult in space. Therefore, in the present work an attempt has been made to explore the possibility of formation of E-cyanomethamine from some simple molecules and...

Radical-radical and radical-neutral interaction schemes are very important for the formation of c... more Radical-radical and radical-neutral interaction schemes are very important for the formation of comparatively complex molecules in low temperature chemistry. An attempt has been made to explore the possibility of formation of complex organic molecules in interstellar medium, through detected interstellar molecules like CH 3 CN and HCOOH. The gas phase reactions were theoretically studied using quantum chemical techniques. We employed the density functional theory (DFT) at the B3LYP/6-311G (d,p) level. The reaction energies, potential barrier and optimized structures of all the geometries, involved in the reaction path, has been discussed. We report the potential energy sufaces for the reactions considered in this work.

ABSTRACT The long carbon chain molecules could be abundant in interstellar medium and play an imp... more ABSTRACT The long carbon chain molecules could be abundant in interstellar medium and play an important role in interstellar chemistry. Methylcyanodiacetylene (MCDA), member of methylcyanopolyyne CH3(C = C)nCN family was �rst detected in interstellar medium with green bank telescope (GBT) toward TMC-1. In this paper structural and vibrational spectral features of MCDA have been studied, using density functional theory (DFT) with di�erent basis sets like and ab-initio theory (MP2) quantum chemical methods. Optimized geometry and infrared spectra have been calculated and a complete vibrational assignment based on potential energy distribution along the internal coordinates has been reported.

Origins of Life and Evolution of Biospheres, 2014

Acrylonitrile (CH 2 CHCN) was first detected in dense molecular cloud SgrB2. The synthesis of thi... more Acrylonitrile (CH 2 CHCN) was first detected in dense molecular cloud SgrB2. The synthesis of this interstellar molecule is reported to be quite difficult. Therefore, in the present work an attempt has been made to explore the possibility of formation of acrylonitrile from some simple molecules and radicals detected in interstellar space by radical-radical interaction scheme, both in the gas phase and in the icy grains. All calculations are performed using quantum chemical methods with density functional theory (DFT) at the B3LYP/6-311G (d,p) level and Møller-Plesset perturbation theory at the MP2/6-311G (d,p) level. In the discussed chemical pathway, the reaction is found to be totally exothermic and barrier less giving rise to a high probability of acrylonitrile formation in Interstellar space.

Monthly Notices of the Royal Astronomical Society, 2021

Monthly Notices of the Royal Astronomical Society, 2021

Springer Proceedings in Physics, 2019

Acetaldehyde is a well-known interstellar molecule which is important for astrochemistry as it ca... more Acetaldehyde is a well-known interstellar molecule which is important for astrochemistry as it can undergo reaction with nitrogen-containing chemical species and can form amino acids or their precursors. Quantum chemical calculations at wB97XD/6-311++G(2d,p) level of theory were performed to study its formation mechanism from the reaction between atomic carbon C(3P) and methanol adsorbed on the surface of interstellar water ice. It was observed that acetaldehyde is formed from a two-step mechanism where the first step is a barrier-mediated step which generates radicals CH3 and H–CO followed by a barrierless addition of these radicals in interstellar ice (step 2). Due to a proton relay mechanism, the entrance barrier is very small and the formation of acetaldehyde is observed to be very efficient in the interstellar ice.

Organic Chemistry Plus

N-methylformamide (NMF), E & Z containing an amide bond, a vital component of peptides, is one of... more N-methylformamide (NMF), E & Z containing an amide bond, a vital component of peptides, is one of the simplest derivatives of formamides. It is detected towards the hot molecular core of the Sgr B2(N2) molecular cloud with the Atacama Large Millimeter/submillimeter Array (ALMA). It is proposed that the radical-molecule mechanism can be used as a strong contrivance to investigate the formation of NMF in the interstellar medium (ISM) via some interstellar molecules like methylidene CH2(1Σ1 & 3Σ1) and formamide (NH2CHO). The density functional theory (DFT) at B3LYP/6-311G (d,p) has been applied to study the mechanisms. All the possible cases of E- & Z-NMF formation with singlet and triplet CH2 have been investigated. It is found that the formation of E-NMF with CH2(1Σ1) and Z-NMF with CH2(3Σ1) is more feasible and favorable in comparison to E-NMF formation from CH2(3Σ1) and Z-NMF with CH2(1Σ1).

International Journal of Astrobiology, 2020

The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectivel... more The formation mechanism of linear and isopropyl cyanide (hereafter n-PrCN and i-PrCN, respectively) in the interstellar medium (ISM) has been proposed from the reaction between some previously detected small cyanides/cyanide radicals and hydrocarbons/hydrocarbon radicals. n-PrCN and i-PrCN are nitriles therefore, they can be precursors of amino acids via Strecker synthesis. The chemistry of i-PrCN is especially important since it is the first and only branched molecule in ISM, hence, it could be a precursor of branched amino acids such as leucine, isoleucine, etc. Therefore, both n-PrCN and i-PrCN have significant astrobiological importance. To study the formation of n-PrCN and i-PrCN in ISM, quantum chemical calculations have been performed using density functional theory at the MP2/6-311++G(2d,p)//M062X/6-311+G(2d,p) level. All the proposed reactions have been studied in the gas phase and the interstellar water ice. It is found that reactions of small cyanide with hydrocarbon radi...

Journal of Molecular Structure

Research in Astronomy and Astrophysics

Monthly Notices of the Royal Astronomical Society

Astrophysics and Space Science

Origins of Life and Evolution of Biospheres

Research in Astronomy and Astrophysics

The European Physical Journal D

The long carbon chain molecules could be abundant in interstellar medium and play an important ro... more The long carbon chain molecules could be abundant in interstellar medium and play an important role in interstellar chemistry. Methylcyanodiacetylene (MCDA), member of methylcyanopolyyne CH 3 (C = C) n CN family was first detected in interstellar medium with green bank telescope (GBT) toward TMC-1. In this paper structural and vibrational spectral features of MCDA have been studied, using density functional theory (DFT) with different basis sets like and ab-initio theory (MP2) quantum chemical methods. Optimized geometry and infrared spectra have been calculated and a complete vibrational assignment based on potential energy distribution along the internal coordinates has been reported. Green Bank Telescope (GBT) toward the Taurus molec

Radical-radical and radical-neutral interaction schemes are very important for the formation of c... more Radical-radical and radical-neutral interaction schemes are very important for the formation of comparatively complex molecules in low temperature chemistry. An attempt has been made to explore the possibility of formation of complex organic molecules in interstellar medium, through detected interstellar molecules like CH 3 CN and HCOOH. The gas phase reactions were theoretically studied using quantum chemical techniques. We employed the density functional theory (DFT) at the B3LYP/6-311G (d,p) level. The reaction energies, potential barrier and optimized structures of all the geometries, involved in the reaction path, has been discussed. We report the potential energy sufaces for the reactions considered in this work.

E- Cyanomethamine is a newly detected molecules in Sgr B2(N) in 2013. E-Cyanomethanimine, HNCHCN,... more E- Cyanomethamine is a newly detected molecules in Sgr B2(N) in 2013. E-Cyanomethanimine, HNCHCN, is a slightly unsaturated sibling of aminoacetonitrile, H2NCH2CN. The detection of interstellar E-cyanomethanimine (E-HNCHCN), toward Sgr B2 (N) in a publicly available GBT spectral survey has been made using a reaction product screening method. In view of significance of the molecule C2N2H2 in reactions leading to the formation of adenine, which is one of four nucleobases that form the "rungs" seen on the double-helix, ladder-like structure of DNA, an attempt has been made in the present quantum chemical study to understand the reaction mechanism involving hydrogen and NCCN molecule that may lead to the formation of E-cyanomethamine in interstellar molecular clouds.The synthesis of the molecule is reported to be difficult in space. Therefore, in the present work an attempt has been made to explore the possibility of formation of E-cyanomethamine from some simple molecules and...

Radical-radical and radical-neutral interaction schemes are very important for the formation of c... more Radical-radical and radical-neutral interaction schemes are very important for the formation of comparatively complex molecules in low temperature chemistry. An attempt has been made to explore the possibility of formation of complex organic molecules in interstellar medium, through detected interstellar molecules like CH 3 CN and HCOOH. The gas phase reactions were theoretically studied using quantum chemical techniques. We employed the density functional theory (DFT) at the B3LYP/6-311G (d,p) level. The reaction energies, potential barrier and optimized structures of all the geometries, involved in the reaction path, has been discussed. We report the potential energy sufaces for the reactions considered in this work.

ABSTRACT The long carbon chain molecules could be abundant in interstellar medium and play an imp... more ABSTRACT The long carbon chain molecules could be abundant in interstellar medium and play an important role in interstellar chemistry. Methylcyanodiacetylene (MCDA), member of methylcyanopolyyne CH3(C = C)nCN family was �rst detected in interstellar medium with green bank telescope (GBT) toward TMC-1. In this paper structural and vibrational spectral features of MCDA have been studied, using density functional theory (DFT) with di�erent basis sets like and ab-initio theory (MP2) quantum chemical methods. Optimized geometry and infrared spectra have been calculated and a complete vibrational assignment based on potential energy distribution along the internal coordinates has been reported.

Origins of Life and Evolution of Biospheres, 2014

Acrylonitrile (CH 2 CHCN) was first detected in dense molecular cloud SgrB2. The synthesis of thi... more Acrylonitrile (CH 2 CHCN) was first detected in dense molecular cloud SgrB2. The synthesis of this interstellar molecule is reported to be quite difficult. Therefore, in the present work an attempt has been made to explore the possibility of formation of acrylonitrile from some simple molecules and radicals detected in interstellar space by radical-radical interaction scheme, both in the gas phase and in the icy grains. All calculations are performed using quantum chemical methods with density functional theory (DFT) at the B3LYP/6-311G (d,p) level and Møller-Plesset perturbation theory at the MP2/6-311G (d,p) level. In the discussed chemical pathway, the reaction is found to be totally exothermic and barrier less giving rise to a high probability of acrylonitrile formation in Interstellar space.