小分子烃的脱附动力学和Binding Energies
Desorption Kinetics and Binding Energies of Small Hydrocarbons
摘要：
小分子烃是原恒星和原行星环境中重要的有机储层。在恒星和行星形成的不同阶段，需要对这些碳氢化合物的解吸温度和结合能进行约束，以准确预测这些分子在冰与气相中的存在位置。通过一系列程序升温脱附（TPD）实验，我们约束了2碳和3碳碳氢化合物的结合能（C $_{2}$ H $_{2}$ -乙炔，C $_{2}$ H $_{2}$-乙烯，C $_{2}$ H $_{6}$ -乙烷，C $_{3}$ H $_{4}$ -丙炔，C $_{3}$ H $_{6}$ -丙烯，和C $_{3}$ H $_{8}$ -丙烷）在纯无定形冰的情况下为2200-4200 K，在致密无定形H $_{2}$ O的情况下为2400-4400 K，在多孔无定形H $_{2}$ O的情况下为2800-4700 K。3碳碳氢化合物的结合能总是大于2碳碳氢化合物的结合能。在2-和3-碳烃族中，炔（即，最不饱和的）烃显示出最大的结合能，而烷烃和烯烃的结合能是相当的。与纯冰相比，水冰基质上的结合能高出$\sim$ 5-20%，这与对其他挥发性分子如CO和N $_{2}$测量的结合能相比是小的增加。因此，在烃的情况下，H $_{2}$ O对升华前沿位置（即，雪线）在原行星盘。
英文摘要：
Small hydrocarbons are an important organic reservoir in protostellar and protoplanetary environments. Constraints on desorption temperatures and binding energies of such hydrocarbons are needed for accurate predictions of where these molecules exist in the ice vs. gas-phase during the different stages of star and planet formation. Through a series of temperature programmed desorption (TPD) experiments, we constrain the binding energies of 2 and 3-carbon hydrocarbons (C$_{2}$H$_{2}$ - acetylene, C$_{2}$H$_{4}$ - ethylene, C$_{2}$H$_{6}$ - ethane, C$_{3}$H$_{4}$ - propyne, C$_{3}$H$_{6}$ - propene, and C$_{3}$H$_{8}$ - propane) to 2200-4200 K in the case of pure amorphous ices, to 2400-4400 K on compact amorphous H$_{2}$O, and to 2800-4700 K on porous amorphous H$_{2}$O. The 3-carbon hydrocarbon binding energies are always larger than the 2-carbon hydrocarbon binding energies. Within the 2- and 3-carbon hydrocarbon families, the alkynes (i.e., least-saturated) hydrocarbons exhibit the largest binding energies, while the alkane and alkene binding energies are comparable. Binding energies are $\sim$5-20% higher on water ice substrates compared to pure ices, which is a small increase compared to what has been measured for other volatile molecules such as CO and N$_{2}$. Thus in the case of hydrocarbons, H$_{2}$O has a less pronounced effect on sublimation front locations (i.e., snowlines) in protoplanetary disks.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
