An Original FORTRAN Code Combined with an XMGRACE© Graphical Routine Aimed at the Parameter Calculations and Drawing of Newton Diagrams for Crossed Molecular Beams (CMB) Experiments Planning

Abstract

This work presents a detailed computational method for analyzing and visually representing molecular collision dynamics in crossed molecular beam (CMB) experiments. An original UNIX-based FORTRAN code was created to calculate important kinematic parameters and build Newton diagrams for reactive systems where two monoenergetic beams intersect at any angle between 0° and 180°. The program finds center-of-mass velocities, collisional energies, product scattering velocities, angular ranges, and coordinate changes between laboratory and center-of-mass reference frames, using the principles of classical mechanics. A related XMGRACE-compatible routine creates high-resolution Newton diagrams that are ready for publication. This allows users to visualize reaction kinematics, scattering circles, and time-of-flight (TOF) detection angles accurately. An extra DOS/GW-Basic executable is included for quick on-screen visualization. The method has been thoroughly tested with different reactive channels and various chemical systems. By combining analytical derivations with automated graphical output, the tool provides a flexible platform for planning CMB experiments, interpreting dynamic results, and comparing theoretical predictions with observed scattering behavior. The codes are free for scientific use with proper credit.