title: Collision energy dependence of state-to-state differential cross sections for rotationally inelastic scattering of H2O by He.
abstract: The inelastic scattering of H2O by He as a function of collision energy in the range 381 cm-1to 763 cm-1at an energy interval of approximately 100 cm-1has been investigated in a crossed beam experiment using velocity map imaging. Change in collision energy was achieved by varying the collision angle between the H2O and He beam. We measured the state-to-state differential cross section (DCS) of scattered H2O products for the final rotational states JKaKc= 110, 111, 221and 414. Rotational excitation of H2O is probed by (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectroscopy. DCS measurements over a wide range of collision energies allowed us to probe the H2O-He potential energy surface (PES) with greater detail than in previous work. We found that a classical approximation of rotational rainbows can predict the collision energy dependence of the DCS. Close-coupling quantum mechanical calculations were used to produce DCS and partial cross sections. The forward-backward ratio (FBR), is introduced here to compare the experimental and theoretical DCS. Both theory and experiments suggest that an increase in the collision energy is accompanied with more forward scattering.
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands.
authors.forename: Gautam
authors.initials: G
authors.lastname: Sarma
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands.
authors.forename: Ashim Kumar
authors.initials: AK
authors.lastname: Saha
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands.
authors.forename: Chandan Kumar
authors.initials: CK
authors.lastname: Bishwakarma
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands.
authors.forename: Roy
authors.initials: R
authors.lastname: Scheidsbach
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan.
authors.forename: Chung-Hsin
authors.initials: CH
authors.lastname: Yang
authors.affiliation: Radboud University Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands.
authors.forename: David
authors.initials: D
authors.lastname: Parker
authors.affiliation: Univ. Grenoble Alpes and CNRS, IPAG, F-38000 Grenoble, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Wiesenfeld
authors.affiliation: Max-Planck-Institut für Dynamik und Selbst-Organisation, Am Faßberg 17, D-37077 Göttingen, Germany.
authors.forename: Udo
authors.initials: U
authors.lastname: Buck
authors.affiliation: Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, Joseph Priestley Building, Mile End Road, London, E1 4NS, UK. s.marinakis@qmul.ac.uk.
authors.forename: Lazaros
authors.initials: L
authors.lastname: Mavridis
authors.affiliation: Department of Chemistry and Biochemistry, School of Biological and Chemical Sciences, Queen Mary University of London, Joseph Priestley Building, Mile End Road, London, E1 4NS, UK. s.marinakis@qmul.ac.uk.
authors.forename: Sarantos
authors.initials: S
authors.lastname: Marinakis