This work reports experiments on the catalytic interaction occurring between polycyclic aromatic hydrocarbon (PAH) molecules and TiO₂ dust grain surfaces under vacuum conditions. The investigation sheds light on the potential catalytic pathways that TiO₂ dust surfaces provide in the hydrogenation of PAH molecules and the chemistry that can be driven by PAH-dust interactions under vacuum conditions. Naphthalene, anthracene, and coronene were chosen as the PAH molecules, while titanium dioxide was selected as the dust analog. PAH samples and dust analog mixtures were studied under vacuum for 24 h while monitored via diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The acquired spectra show that PAH molecules are hydrogenated when in contact with TiO₂ dust particles without the need for external energy or hydrogen sources. Our results suggest that linear PAHs undergo a similar hydrogenation process where the dominant species are fully hydrogenated PAHs. For larger condensed PAHs, the hydrogenation process yields partially hydrogenated molecules. Fully hydrogenated species can be identified by a band around 2960 cm^–1, while partially hydrogenated species produce a band around 2825 cm^–1. In the case of the production of hydrogenated species, our results suggest that the smaller the PAH, the faster the hydrogenation rate.

中文翻译：

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多环芳烃与粉尘颗粒表面的相互作用：真空条件下多环芳烃分子的催化加氢

这项工作报告了在真空条件下多环芳烃（PAH）分子与TiO ₂尘埃颗粒表面之间发生催化相互作用的实验。这项研究揭示了TiO ₂尘埃表面在PAH分子氢化中提供的潜在催化途径以及在真空条件下可由PAH尘埃相互作用驱动的化学反应。选择萘，蒽和and烯作为PAH分子，同时选择二氧化钛作为粉尘类似物。PAH样品和粉尘类似物混合物在真空下研究了24小时，同时通过漫反射红外傅里叶变换光谱（DRIFTS）进行了监测。所获得的光谱表明，PAH分子与TiO ₂接触时被氢化不需要外部能源或氢源的粉尘颗粒。我们的结果表明，线性多环芳烃经历了类似的氢化过程，其中主要物质是完全氢化的多环芳烃。对于较大的缩合PAH，氢化过程会产生部分氢化的分子。可以通过2960 cm ^–1左右的谱带来识别完全氢化的物质，而通过部分氢化的物种可以产生2825 cm ^–1的谱带。在生产氢化物质的情况下，我们的结果表明，PAH越小，氢化速度越快。