SIMULATION OF THE SPIN-VIBRONIC STRUCTURE IN THE GROUND ELECTRONIC STATE AND EMISSION SPECTRA INTENSITIES FOR CH$_3$O RADICAL

Abstract

Methoxy is a radical ubiquitous in the reactions of combustion and oxidation of hydrocarbon compounds in the atmosphere. Because of its relatively small size and degenerate $\tilde{X}$$^2$E ground electronic state, it presents a benchmark system for theoreticians to study the multimode Jahn-Teller (JT) effect in the presence of spin-orbit interaction. We have coupled an effective Hamiltonian, including Jahn-Teller coupling terms of up to 3$^d$ order, with a powerful computational engine that allows for quick calculations of spin-vibronic eigenstates and, correspondingly, eigenfunctions from which spectrum intensities can be derived. A graphical user interface, coupled with this computational core, helps to visualize the simulated spectra and compare them with the experimental traces. We simulate and discuss the intensities and spin-vibronic level positions, that we have observed in 4 dispersed fluorescence spectra obtained by pumping the $\tilde{A}$ state vibrational levels 3$^5$, 3$^1$4$^1$, 3$^3$5$^1$ and 3$^3$6$^1$, and complementary data that have been obtained in SEP experiments of Temps and coworkers}.