Conformation and spectroscopy study of cycloheptoxy radical

Alkoxy radicals are important intermediates in the formation of tropospheric ozone. The spectroscopic identification and characterization of these species are important for understanding their chemistry in the atmosphere. In this work, we report the observation of the laser induced fluorescence (LIF) excitation spectrum of cycloheptoxy radical. The spectrum was assigned preliminary to the lowest energy twist-chair conformer (TC-i) of cycloheptoxy. The whole picture of the interconversions at ground state between different conformers of cycloheptoxy radicals was described by density functional theory calculations. The results revealed that despite the ring strain, the seven-membered ring alkoxy radical could exist in the supersonic jet-cooled condition. The decomposition and the low energy barrier pseudorotation between twist-chair conformers might be the reason of the much quieter spectrum of cycloheptoxy compared with the LIF spectrum of cyclohexoxy.