Quantum Mechanical Rate Coefficient of Formation of HD Molecule at Ultracold Temperatures: Its Importance in Interstellar Cooling

Authors

  • Ranga Santosh Department of Chemistry, Birla Institute of Technology and Science Pilani, Hyderabad Campus, Hyderabad 500078
  • Subhas Ghosal Department of Chemistry, Birla Institute of Technology and Science Pilani, Hyderabad Campus, Hyderabad 500078

DOI:

https://doi.org/10.26713/jamcnp.v2i3.338

Keywords:

Ultracold HD, Reaction dynamics

Abstract

Molecular hydrogen and its isotope HD acted as one of the most important interstellar coolants in the primordial gas medium. In this paper, we present accurate time-independent quantum mechanical (TIQM) rate coefficients of formation of ultracold HD molecules by \({\rm D} +{\rm H}_2(v,j)\to {\rm HD}(v', j')+{\rm H}\) reaction at very low collision energy. State resolved integral cross sections between different rotational \((j)\) and vibrational \((v)\) levels and corresponding Boltzmann-averaged thermal rate coefficients are computed between temperature \(\rm T = 10^{-8}K\)-\(\rm 10K\). We found the exponential decrease of the rate coefficients with reducing temperature following Arrhenius' empirical equation is not valid at ultracold temperature limit. At lower temperatures, the rate coefficients become independent of temperature (constant) and Wigner's threshold laws are obeyed. Since cooling of the primordial gases lead to the formation of the first structures of the universe, inclusion of the accurate low-temperature rate coefficients will lead to improved modeling for the evolution of the early universe.

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References

S. W. Hawking and G. F. R. Ellis, The Large Scale Structure of Space-time, Cambridge University Press (1973).

P. C. Stancil, S. Lepp and A. Dalgarno, The deuterium chemistry of the early universe, Astrophys. J. 509 (1998), 1.

S. C. O. Glover and T. Abel, Uncertainties in (rm H_2) and HD chemistry and cooling and their role in early structure formation, Monthly Notices of the Royal Astronomical Society 388 (2008), 1627–1651.

R. S. Sutherland and M. A. Dopita, Cooling functions for low-density plasmas, The Astrophysical J. Supplement Series 88 (1993), 253–327.

S. L. Mielke, K. A. Peterson, D. W. Schwenke, D. G. Carrett, B. C. Truhlar, J. V. Michael, M.-C. Su and J. W. Sutherland, (rm H + H_2) thermal reaction: A convergence of theory and experiment, Phys. Rev. Lett. 91 (2003), 063201.

F. J. Aoiz and V. J. Herrero, M. P. de Miranda and V. Saez Rabanos, Constraints at the transition state of the (rm D+H_2) reaction: quantum bottlenecks vs. stereodynamics, Phys. Chem. Chem. Phys. 9 (2007), 5367–5373.

I. Simbotin, S. Ghosal and R. Cí´té, A case study in ultracold reactive scattering: (rm D+H_2), Phys. Chem. Chem. Phys. 13 (2011), 19148–19155.

M. Peleg, M. D. Normand and M. G. Corradini, Arrhenius equation revisited, Critical reviews in Food Science and Nutrition 52 (2012), 830–851.

L. M. Delves, Tertiary and general-order collisions (II), Nuc. Phys. 20 (1960), 275–308.

R. T Pack and G. A. Parker, Quantum reactive scattering in three dimensions using hyperspherical (APH) coordinates theory, J. Chem. Phys. 87 (1987), 3888–3921.

G. C. Schatz, Quantum reactive scattering using hyperspherical coordinates: results for (rm H+H_2) and (rm Cl + HCl), Chem. Phys. Lett. 150 (1988), 92–98.

D. Skouteris, J. F. Castillo and D. E. Manolopoulos, Abc: a quantum reactive scattering program, Comp. Phys. Comm. 133 (2000), 128–135.

D. E. Manolopoulos, An improved log derivative method for inelastic scattering, J. Chem. Phys. 85 (1986), 6425–6429.

J. Hazra, B. P. Ruzic, J. L. Bohn and N. Balakrishnan, Quantum defect theory for cold chemistry with product-quantum-state resolution, Phys. Rev. A 90 (2014), 062703.

A. I. Boothroyd, W. J. Keogh, P. G. Martin and M. R. Peterson, A refined (rm H_3) potential energy surface, J. Chem. Phys. 104 (1996), 7139–7152.

E. P. Wigner, On the behavior of cross sections near thresholds, Phys. Rev. 73 (1948), 1002–1009.

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Published

2015-12-28
CITATION

How to Cite

Santosh, R., & Ghosal, S. (2015). Quantum Mechanical Rate Coefficient of Formation of HD Molecule at Ultracold Temperatures: Its Importance in Interstellar Cooling. Journal of Atomic, Molecular, Condensed Matter and Nano Physics, 2(3), 179–186. https://doi.org/10.26713/jamcnp.v2i3.338

Issue

Vol. 2 No. 3 (2015)

Section

Research Article

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