Millimeter and centimeter observations are discovering an increasing number of interstellar complex organic molecules (iCOMs) in a large variety of star-forming sites, from the earliest stages of star formation to protoplanetary disks and in comets. In this context it is pivotal to understand how the solid-phase interactions between iCOMs and grain surfaces influence the thermal desorption process and, therefore, the presence of molecular species in the gas phase. In the laboratory, it is possible to simulate the thermal desorption process, deriving important parameters such as the desorption temperatures and energies. We report new laboratory results on temperature-programmed desorption from olivine dust of astrophysical relevant ice mixtures of water, acetonitrile, and acetaldehyde. We found that in the presence of grains, only a fraction of acetaldehyde and acetonitrile desorb at about 100 K and 120 K, respectively, while 40% of the molecules are retained by fluffy grains of the order of 100 μm up to temperatures of 190–210 K. In contrast with the typical assumption that all molecules are desorbed in regions with temperatures higher than 100 K, this result implies that about 40% of the molecules can survive on the grains enabling the delivery of volatiles toward regions with temperatures as high as 200 K and shifting inwards the position of the snow lines in protoplanetary disks. These studies offer a necessary support to interpret observational data and may help our understanding of iCOM formation, providing an estimate of the fraction of molecules released at various temperatures.

毫米和厘米的观测发现，从恒星形成的最早阶段到原行星盘和彗星，在各种各样的恒星形成地点发现了越来越多的星际复杂有机分子 (iCOM)。在这种情况下，了解 iCOM 和晶粒表面之间的固相相互作用如何影响热解吸过程以及气相中分子种类的存在至关重要。在实验室中，可以模拟热解吸过程，得出解吸温度和能量等重要参数。我们报告了新的实验室结果，从橄榄石尘埃中的水、乙腈和乙醛的天体物理相关冰混合物的程序升温解吸。我们发现在有谷物的情况下，μ m 高达 190–210 K 的温度。与所有分子在温度高于 100 K 的区域解吸的典型假设相反，该结果意味着大约 40% 的分子可以在晶粒上存活，从而能够传递向温度高达 200 K 的区域挥发，并向内移动原行星盘中雪线的位置。这些研究为解释观测数据提供了必要的支持，并可能有助于我们了解 iCOM 的形成，提供对在不同温度下释放的分子分数的估计。