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The Journal of Chemical Physics· 2026Q1

Beyond rare gases: Cooling of trapped BN− ions by H2 molecules

Sahil Rana, Upakarasamy Lourderaj, Kousik Giri, Lola González‐Sánchez et al.

Short summary

Quantum dynamics calculations reveal that H2 molecules, specifically para-H2, are significantly more effective than rare gases (He, Ar) at cooling trapped BN− ions, achieving lower temperatures.

AI-generated from the title and abstract; the full text is not read.

Key points

  • Quantum dynamics simulations were used to model the collisional cooling of BN− ions by H2 molecules in a cold trap.
  • A highly accurate four-dimensional interaction potential energy surface was computed using ab initio methods and fitted with an artificial neural network.
  • State-to-state rotationally inelastic cross sections and rate coefficients were calculated for ortho- and para-H2.
  • H2 molecules, especially para-H2, show greater cooling efficiency for BN− ions compared to rare gases (He, Ar).

AI-generated from the title and abstract; the full text is not read.

Abstract

Quantum dynamics of collisional cooling of the BN- anion in a cold trap is carried out by using the ortho- and para-H2 molecules as a buffer gas. The calculations are performed using the full four-dimensional interaction potential energy surface in which both BN- and H2 are treated as vibrationless rigid rotors, computed from ab initio methods and further accurately fitted using an artificial neural network approach. Relevant state-to-state rotationally inelastic cross sections are computed from quantum methods, and the ensuing inelastic rate coefficients for the temperatures of interest are obtained. The latter are employed in modeling the cooling process at a variety of trap conditions. The results are discussed in the context of earlier data obtained using the rare gases He and Ar as buffer gases in the same trap. The effects of having either para- or ortho-H2 as a collision partner are analyzed.

The authors' abstract, as published at the source. The Journal of Chemical Physics, 2026 · DOI ↗

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Field: Atomic and Molecular Physics, and Optics

Atomic and Molecular Physics, and OpticsPhysics and Astronomy