Rotationally inelastic scattering of ND₃ with H₂ as a probe of the intermolecular potential energy surface

Abstract

Differential cross sections (DCSs) are reported for rotationally inelastic scattering of ND₃ with H₂, measured using a crossed molecular beam apparatus with velocity map imaging (VMI). ND₃ molecules were quantum-state selected in the ground electronic and vibrational levels and, optionally, in the j^±_k = 1₁⁻  rotation-inversion level prior to collisions. Inelastic scattering of state-selected ND₃ with H₂ was measured at the mean collision energy of 580 cm⁻¹ by resonance-enhanced multiphoton ionisation spectroscopy and VMI of ND₃ in selected single final j'^±_k' levels. Comparison of experimental DCSs with close-coupling quantum-mechanical scattering calculations serves as a test of a recently reported ab initio potential energy surface. Calculated integral cross sections reveal the propensities for scattering into various final j'^±_k' levels of ND₃ and differences between scattering by ortho and para H₂. Integral and differential cross sections are also computed at a mean collision energy of 430 cm^–1 and compared to our recent results for inelastic scattering of state-selected ND₃ with He.

Keywords:

• molecular collisions
• crossed-beam scattering
• ND₃-H₂
• differential cross sections
• velocity map imaging

Acknowledgements

The Nijmegen group acknowledges financial support from NWO-CW ECHO (for Ashim K. Saha). The Bristol group thanks EPSRC for funding via the EPSRC Programme Grant EP/G00224X. These two groups were part of the EU Initial Training Network ICONIC, which provided financial support for Ondřej Tkáč and for visits between the two institutions. Jérôme Loreau acknowledges support from the Belgian Fund for Scientific Research - FNRS and the Wiener-Anspach Foundation. Paul J. Dagdigian and Qianli Ma acknowledge support from the US National Science Foundation (grant no. CHE-1313332); they are also grateful for the advice and encouragement of Millard Alexander.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The Nijmegen group acknowledges financial support from [NWO-CW ECHO] (for Ashim K. Saha). The Bristol group thanks EPSRC for funding [grant number EP/G00224X]. These two groups were part of the EU Initial Training Network ICONIC, which provided financial support for Ondřej Tkáč and for visits between the two institutions. Jérôme Loreau acknowledges support from the Belgian Fund for Scientific Research - FNRS and the Wiener-Anspach Foundation. Paul J. Dagdigian and Qianli Ma acknowledge support from the US National Science Foundation [grant number CHE-1313332].