High resolution Dopplerimetry of correlated angular and quantum state-resolved CO2 scattering dynamics at the gas–liquid interface

Abstract

Full three dimensional (3D) translational distributions for quantum state-resolved scattering dynamics at the gas–liquid interface are presented for experimental and theoretical studies of CO₂ + perfluorinated surfaces. Experimentally, high resolution absorption profiles are measured as a function of incident (θ_inc) and scattering (θ_scat) angles for CO₂ that has been scattered from a 300 K perfluorinated polyether surface (PFPE) with an incident energy of E_inc = 10.6(8) kcal mol⁻¹. Line shape analysis of the absorption profiles reveals non-equilibrium dynamics that are characterized by trapping–desorption (TD) and impulsive scattering (IS) components, with each channel simply characterized by an effective “temperature” that compares very well with previous results from rotational state analysis [Perkins and Nesbitt, J. Phys. Chem. A, 2008, 112, 9324]. From a theoretical perspective, molecular dynamics (MD) simulations of CO₂ + fluorinated self-assembled monolayer surface (F-SAMs) yield translational probability distributions that are also compared with experimental results. Trajectories are parsed by θ_scat and J, with the results rigorously corrected by flux-to-density transformation and providing comparisons in near quantitative agreement with experiment. 3D flux and velocity distributions obtained from MD simulations are also presented to illustrate the role of in- and out-of-plane scattering.