Collision energy dependence of state-to-state differential cross sections for rotationally inelastic scattering of H2O by He. Issue 6 (27th January 2017)

• Record Type: Journal Article
• Authors: Sarma, Gautam; Saha, Ashim Kumar; Bishwakarma, Chandan Kumar; Scheidsbach, Roy; Yang, Chung-Hsin; Parker, David; Wiesenfeld, Laurent; Buck, Udo; Mavridis, Lazaros; Marinakis, Sarantos
• Is Part Of: Physical chemistry chemical physics. Volume 19:Issue 6(2017)
• Page Start: 4678
• Page End: 4687
• Publication Date: 2017-01-27
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp06495g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The inelastic scattering of H2 O by He as a function of collision energy in the range 381 cm −1 to 763 cm −1 has been investigated using velocity map imaging. Abstract : The inelastic scattering of H2 O by He as a function of collision energy in the range 381 cm −1 to 763 cm −1 at an energy interval of approximately 100 cm −1 has been investigated in a crossed beam experiment using velocity map imaging. Change in collision energy was achieved by varying the collision angle between the H2 O and He beam. We measured the state-to-state differential cross section (DCS) of scattered H2 O products for the final rotational states J K a K c = 110, 111, 221 and 414 . Rotational excitation of H2 O 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 H2 O–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.