We report the hyperfine-resolved rotational spectrum of the gas-phase phenoxy radical in the 8–25 GHz frequency range using cavity Fourier transform microwave spectroscopy. A complete assignment of its complex but well-resolved fine and hyperfine splittings yielded a precisely determined set of rotational constants, spin-rotation parameters, and nuclear hyperfine coupling constants. These results are interpreted with support from high-level quantum chemical calculations to gain detailed insight into the distribution of the unpaired π electron in this prototypical resonance-stabilized radical. The accurate laboratory rest frequencies enable studies of the chemistry of phenoxy in both the laboratory and space. The prospects of extending the present experimental and theoretical techniques to investigate the rotational spectra of isotopic variants and structural isomers of phenoxy and other important gas-phase radical intermediates that are yet undetected at radio wavelengths are discussed.

中文翻译：

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苯氧基自由基的旋转光谱


我们使用腔体傅立叶变换微波光谱报告了 8–25 GHz 频率范围内气相苯氧基自由基的超精细旋转光谱。对其复杂但分辨率良好的精细和超精细分裂的完整分配产生了一组精确确定的旋转常数、自旋旋转参数和核超精细耦合常数。这些结果在高级量子化学计算的支持下进行解释，以详细了解该原型共振稳定自由基中不成对的 π 电子的分布。准确的实验室休息频率使得能够在实验室和太空中研究苯氧基的化学。讨论了扩展现有实验和理论技术来研究苯氧基和其他尚未在无线电波长下检测到的重要气相自由基中间体的同位素变体和结构异构体的旋转光谱的前景。