Formation and photolysis of multifunctional organic nitrates from the reaction of limonene and NO3 radicals

Abstract

Multifunctional organic nitrates (LIM-ONO₂) were formed from the NO₃-initiated oxidation of limonene in the Simulation Chamber for Atmospheric Reactions and Kinetics (SCHARK), detected quantitatively by thermal dissociation cavity ring-down spectroscopy (TD-CRDS) and identified by high-resolution time-of-flight chemical-ionization (iodide) mass spectrometry (HR-ToF-ICIMS). Based on HR-ToF-ICIMS signal intensities, the most abundant LIM-ONO₂ were C₁₀H₁₇NO₄ and C₁₀H₁₇NO₅, together representing >60% of the total LIM-ONO₂ signal. We developed a method for cold-trapping LIM-ONO₂ from the chamber, enabling us to examine their photolysis in the absence of precursor chemicals after re-injection into the SCHARK. The photolytic loss frequency of C₁₀H₁₇NO₄ in the chamber when irradiated with LEDs emitting at 370 ± 13 nm was (1.69 ± 0.06) × 10⁻⁴ s⁻¹. By comparison to the photolysis frequency of a chemical actinometer (Cl₂), we were able to gain insight into the quantum yield (0.3–0.8) and absorption cross section of C₁₀H₁₇NO₄ at these wavelengths and make an estimate of its atmospheric lifetime with respect to photolysis.