Unveiling ultraviolet photodissociation dynamics of SiO from a laser-ablated supersonic beam with time-sliced ion velocity imaging

Abstract

SiO is a widespread molecule found in interstellar space, and its dissociation requires a substantial input of energy due to its high bond energy of 8.34 eV. The present study initially demonstrated across a broad range of ultraviolet (UV) wavelengths (243–288 nm) the one-photon and two-photon dissociation of SiO molecules, which were generated from the laser ablation of a Si rod colliding with an oxygen molecular beam. The images of Si products obtained through time-sliced ion velocity mapping have revealed the existence of distinct dissociation channels, encompassing Si(³P) + O(³P), Si(¹D) + O(³P), Si(¹D) + O(¹D) and Si(¹S) + O(¹D) from the photodissociation of vibrationally excited SiO(X¹Σ⁺, v) and low-lying electronically excited SiO(C¹Σ⁻, D¹Δ, a³Σ⁺, b³Π, d³Δ and e³Σ⁻) states. These findings contribute to a more comprehensive understanding of silicon chemistry during the combustion of silica-rich meteorites in the Earth's atmosphere, and have wider implications in the fields of atmospheric chemistry, astrochemistry, and combustion science.