Smith R Scott, Kay Bruce D
Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
J Phys Chem B. 2018 Jan 18;122(2):587-594. doi: 10.1021/acs.jpcb.7b05102. Epub 2017 Jul 18.
The desorption kinetics for benzene and cyclohexane from a graphene covered Pt(111) surface were investigated using temperature-programmed desorption (TPD). The benzene desorption spectra show well-resolved monolayer and multilayer desorption peaks. The benzene monolayer and submonolayer TPD spectra for coverages greater than ∼0.1 ML have nearly the same desorption peak temperature and have line shapes which are consistent with first-order desorption kinetics. For benzene coverages greater than 1 ML, the TPD spectra align on a common leading edge which is consistent with zero-order desorption. An "inversion" procedure in which the prefactor is varied to find the value that best reproduces the entire set of experimental desorption spectra was used to analyze the benzene data. The inversion analysis of the benzene TPD spectra yielded a desorption activation energy of 54 ± 3 kJ/mol with a prefactor of 10 s. The TPD spectra for cyclohexane also have well-resolved monolayer and multilayer desorption features. The desorption leading edges for the monolayer and the multilayer TPD spectra are aligned indicating zero-order desorption kinetics in both cases. An Arrhenius analysis of the monolayer cyclohexane TPD spectra yielded a desorption activation energy of 53.5 ± 2 kJ/mol with a prefactor of 10 ML s.
利用程序升温脱附（TPD）研究了苯和环己烷从石墨烯覆盖的Pt(111)表面的脱附动力学。苯的脱附谱显示出分辨良好的单层和多层脱附峰。对于覆盖率大于约0.1 ML的苯单层和亚单层TPD谱，具有几乎相同的脱附峰温度，并且线形与一级脱附动力学一致。对于苯覆盖率大于1 ML，TPD谱在一个共同的前沿对齐，这与零级脱附一致。采用一种“反演”程序，其中改变前因子以找到最能重现整个实验脱附谱集的值，用于分析苯的数据。苯TPD谱的反演分析得到脱附活化能为54±3 kJ/mol，前因子为10 s。环己烷的TPD谱也具有分辨良好的单层和多层脱附特征。单层和多层TPD谱的脱附前沿对齐，表明两种情况下均为零级脱附动力学。对单层环己烷TPD谱的阿仑尼乌斯分析得到脱附活化能为53.5±2 kJ/mol，前因子为10 ML s。
