Experimental and Theoretical Studies of Hyperthermal N + O₂ Collisions

Area of Science:

• Chemical Physics
• Molecular Dynamics
• Reaction Mechanisms

Background:

• Understanding the dynamics of hyperthermal collisions is crucial for atmospheric chemistry and combustion processes.
• The reaction between nitrogen atoms and oxygen molecules (N + O2) is a fundamental process with implications for airglow and atmospheric modeling.

Purpose of the Study:

• To experimentally and theoretically investigate the dynamics of hyperthermal N(4S) + O2 collisions.
• To identify and characterize the nonreactive (N + O2) and reactive (NO + O) product channels.
• To elucidate the underlying dynamical pathways and energy distributions in these collisions.

Main Methods:

• Crossed molecular beams experiments with velocity- and angle-resolved product detection.
• Quasiclassical trajectory (QCT) calculations utilizing two distinct potential energy surfaces (PES-I and PES-II).
• Comparison of experimental results with theoretical predictions from QCT calculations.

Main Results:

• Both nonreactive N + O2 and reactive NO + O products scattered forward in the center-of-mass frame.
• Nonreactive products retained most of the available energy in translation; reactive products showed broad translational energy distributions, indicating internal excitation of NO.
• Experimental and theoretical data suggested at least two dynamical pathways for NO + O formation, potentially involving doublet (12A') and quartet (14A') electronic states.

Conclusions:

• The study successfully elucidated the complex dynamics of hyperthermal N + O2 collisions.
• Good agreement was found between experimental and theoretical results, validating the proposed reaction mechanisms.
• The findings provide valuable insights into the energy partitioning and scattering behavior of both reactive and nonreactive channels.