Abstract The photofragmentation of the isoxazole molecules producing ionized atomic and molecular fragments was investigated in the photon energy range of 9–32 eV, using synchrotron radiation excitation combined with ion time-of-flight spectrometry. Twenty-one well resolved cations were identified in the mass spectra of the isoxazole, and their appearance energies were determined. The yield curves of these cations were obtained in the photon energy ranges from their appearance energies up to 32 eV. Moreover, the total ion yield of isoxazole was recorded with high precision in the photon energy range of 9.9–10.5 eV. This allowed the determination of the adiabatic ionization energy of 9.96 (0.02) eV in excellent agreement with earlier spectroscopic studies. Our results show that the dissociative ionization of isoxazole starts from the ring-opening and isomerization of isoxazole, and further it follows strictly through its ionic states. Possible ionic fragmentation channels yielding particular ions are discussed.

中文翻译：

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异恶唑分子的真空紫外光电离和离子碎裂

摘要 使用同步辐射激发结合离子飞行时间光谱法研究了在 9-32 eV 光子能量范围内产生电离原子和分子碎片的异恶唑分子的光碎裂。在异恶唑的质谱图中鉴定了 21 个解析良好的阳离子，并确定了它们的出现能量。这些阳离子的产率曲线是在从它们的出现能量到 32 eV 的光子能量范围内获得的。此外，异恶唑的总离子产率在 9.9-10.5 eV 的光子能量范围内以高精度记录。这使得绝热电离能的确定为 9.96 (0.02) eV，与早期的光谱研究非常一致。我们的结果表明，异恶唑的解离电离从异恶唑的开环和异构化开始，并进一步严格遵循其离子状态。讨论了可能产生特定离子的离子碎裂通道。