As host to two accreting planets, PDS 70 provides a unique opportunity to probe the chemical complexity of atmosphere-forming material. We present ALMA Band 6 observations of the PDS 70 disk and report the first chemical inventory of the system. With a spatial resolution of 0.″4–0.″5 (∼50 au), 12 species are detected, including CO isotopologs and formaldehyde, small hydrocarbons, HCN and HCO⁺ isotopologs, and S-bearing molecules. SO and CH₃OH are not detected. All lines show a large cavity at the center of the disk, indicative of the deep gap carved by the massive planets. The radial profiles of the line emission are compared to the (sub)millimeter continuum and infrared scattered light intensity profiles. Different molecular transitions peak at different radii, revealing the complex interplay between density, temperature, and chemistry in setting molecular abundances. Column densities and optical depth profiles are derived for all detected molecules, and upper limits obtained for the nondetections. Excitation temperature is obtained for H₂CO. Deuteration and nitrogen fractionation profiles from the hydrocyanide lines show radially increasing fractionation levels. Comparison of the disk chemical inventory to grids of chemical models from the literature strongly suggests a disk molecular layer hosting a carbon-to-oxygen ratio C/O > 1, thus providing for the first time compelling evidence of planets actively accreting high C/O ratio gas at present time.

作为两颗吸积行星的宿主，PDS 70 提供了一个独特的机会来探测大气形成物质的化学复杂性。我们展示了 PDS 70 圆盘的 ALMA Band 6 观察结果，并报告了该系统的第一个化学清单。空间分辨率为 0.″4–0.″5 (∼50 au)，检测到 12 种物质，包括 CO 同位素和甲醛、小烃类、HCN 和 HCO ⁺同位素以及含硫分子。SO和CH ₃未检测到 OH。所有线条都显示了圆盘中心的一个大空腔，表明大质量行星雕刻出的深沟。线发射的径向分布与（亚）毫米连续谱和红外散射光强度分布进行比较。不同的分子跃迁在不同半径处达到峰值，揭示了密度、温度和化学之间在设置分子丰度方面的复杂相互作用。推导出所有检测到的分子的柱密度和光学深度分布，并为未检测到的分子获得上限。获得 H _{2 的}激发温度CO。来自氢氰化物管线的氘化和氮分馏曲线显示分馏水平呈放射状增加。将盘状化学物质清单与文献中的化学模型网格进行比较，强烈表明存在碳氧比 C/O > 1 的盘状分子层，从而首次提供了行星积极吸积高 C/O 的令人信服的证据目前的比例气体。