Conformational landscape and inertial defect of methoxyphenol isomers studied by mm-wave spectroscopy and quantum chemistry calculations

Jabri, A. [LaLaboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Fontanari, D. [Laboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Roucou, Anthony [UCL] Bray, C. [Laboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Hindle, F. [Laboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Dhont, G. [Laboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Mouret, G. [Laboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Bocquet, R. [Laboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] Cuisset, A. [Lalaboratoire de Physico-Chimie de l’Atmosphère, CNRS EA-4493, Université du Littoral Côte d’Opale, 59140 Dunkerque, France] et al.[show all]

Because methoxyphenols (MP) are emitted in significant quantities during biomass fires and contribute to the secondary organic aerosols formation which impacts the climate, their gas phase monitoring in the atmosphere is crucial and requires accurate rovibrational cross sections determined with a good knowledge of their ground state (GS) and vibrationally excited state (ES) molecular parameters. Therefore,the rotational spectra of the two isomers, 2-MP (guaïacol) and 4-MP (mequinol), have been measured in absorption and in emission at room temperature using a frequency multiplication chain and a mm-wave Fourier transform chirped-pulse spectrometer, respectively. Guided by quantum chemistry calculations, the conformational landscape has been characterised and the observation of only one rotamer in the spectra of 2-MP and 4-MP has been explained. For 2-MP, the most stable conformation is justified by an intramolecular O