Infrared photodesorption of CO from astrophysically relevant ices studied with a free-electron laser
Infrared photodesorption of CO from astrophysically relevant ices studied with a free-electron laser
复制标题
使用自由电子激光研究天体物理相关冰中二氧化碳的红外光解吸
DOI：
10.1039/d3fd00024a
复制
发表时间：
2023
影响因子：
3.4
通讯作者：
Ingman E
中科院分区：
文献类型：
--
作者：
Ingman E
利用荷兰Radboud大学FELIX实验室的FEL-2自由电子激光光源研究了一氧化碳（CO）和含水冰的红外激发和光脱附。研究了18 K时在镀金铜衬底上生长的CO-水混合冰。用与C-O振动共振的光（4.67 μm）照射后，在我们的检测限内没有观察到CO光解吸。CO光脱附是用与水在2.9 μm和12 μm振动模共振的红外光照射的结果。在这些波长的照射之后，也可以看到水冰结构的变化，这改变了混合冰中CO的环境。在任何照射波长下均未观察到水解吸。在两个波长下的光解吸是由于单光子过程。光脱附是由于间接共振光脱附（快）、固体水解离热浴中能量积累产生的光子诱导脱附（慢）和金属基底介导的激光诱导热脱附（慢）的快速和缓慢过程的组合而产生的。在2.9 μm和12 μm的慢过程中，估计的截面分别为1.75 × 10−18 cm 2和1.45 × 10−19 cm 2。
The infrared excitation and photodesorption of carbon monoxide (CO) and water-containing ices have been investigated using the FEL-2 free-electron laser light source at the FELIX laboratory, Radboud University, The Netherlands. CO–water mixed ices grown on a gold-coated copper substrate at 18 K were investigated. No CO photodesorption was observed, within our detection limits, following irradiation with light resonant with the C–O vibration (4.67 μm). CO photodesorption was seen as a result of irradiation with infrared light resonant with water vibrational modes at 2.9 μm and 12 μm. Changes to the structure of the water ice, which modifies the environment of the CO in the mixed ice, were also seen subsequent to irradiation at these wavelengths. No water desorption was observed at any wavelength of irradiation. Photodesorption at both wavelengths is due to a single-photon process. Photodesorption arises due to a combination of fast and slow processes of indirect resonant photodesorption (fast), and photon-induced desorption resulting from energy accumulation in the librational heat bath of the solid water (slow) and metal-substrate-mediated laser-induced thermal desorption (slow). Estimated cross-sections for the slow processes at 2.9 μm and 12 μm were found to be ∼7.5 × 10−18 cm2 and ∼4.5 × 10−19 cm2, respectively.