Hydronium (H₃O⁺) is the smallest member of protonated water. In this work, we use quantum chemical calculations to explore the solvation of H₃O⁺ by adding one CO₂ molecule at a time. The effect of stepwise solvation on infrared spectroscopy, structure, and energetics has been systematically studied. It has been found that the first solvation shell of H₃O⁺ is completed at n = 6. Besides the hydrogen-bond interaction, the --- intermolecular interaction is also responsible for the stabilization of the larger clusters. The transfer of the proton from H₃O⁺ onto CO₂ with the formation of the OCOH⁺ moiety is not observed in the early stage of solvation process. Calculated IR spectra suggest that vibrational frequencies of H-bonded O-H stretching would afford a sensitive probe for exploring the early stage solvation of hydronium by carbon dioxide. IR spectra for the (H₃O⁺)(CO₂)_n (n = 17) clusters could be measured by the infrared photodissociation spectroscopic technique and thus provide a vivid physical picture about how carbon dioxide solvates the hydronium.

水合氢（H ₃ O ⁺）是质子化水的最小成员。在这项工作中，我们使用量子化学计算通过一次添加一个CO ₂分子来探索H ₃ O ⁺的溶剂化作用。逐步溶剂化对红外光谱，结构和高能学的影响已得到系统地研究。已经发现，H ₃ O ⁺的第一个溶剂化壳在n = 6时完成。除了氢键相互作用外，分子间的相互作用也负责稳定较大的团簇。质子从H ₃ O ⁺转移到CO _2上在溶剂化过程的早期未观察到具有OCOH ⁺部分的形成。计算得出的红外光谱表明，氢键键合的OH拉伸的振动频率将为研究二氧化碳早期溶剂化氢鎓提供灵敏的探针。（H ₃ O ⁺）（CO ₂）_n（n = 17）团簇的红外光谱可以通过红外光解光谱技术进行测量，从而提供了有关二氧化碳如何溶解水合氢原子的生动的物理图像。