Desorption of Water from Distinct Step Types on a Curved Silver Crystal

Molecules

Jakrapan Janlamool¹  Dima Bashlakov²  Otto Berg²  Piyasan Praserthdam¹  Bunjerd Jongsomjit¹ 

[1] Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand;Leiden Institute of Chemistry, Leiden University, PO BOX 9502, 2300 RA Leiden, The Netherlands

关键词: silver;    water;    adsorption;    single crystal;    steps;    surface science;   

DOI  :  10.3390/molecules190810845

来源: mdpi

【 摘 要 】

We have investigated the adsorption of H₂O onto the A and B type steps on an Ag single crystal by temperature programmed desorption. For this study, we have used a curved crystal exposing a continuous range of surface structures ranging from [5(111) × (100)] via (111) to [5(111) × (110)]. LEED and STM studies verify that the curvature of our sample results predominantly from monoatomic steps. The sample thus provides a continuous array of step densities for both step types. Desorption probed by spatially-resolved TPD of multilayers of H₂O shows no dependence on the exact substrate structure and thus confirms the absence of thermal gradients during temperature ramps. In the submonolayer regime, we observe a small and linear dependence of the desorption temperature on the A and B step density. We argue that such small differences are only observable by means of a single curved crystal, which thus establishes new experimental benchmarks for theoretical calculation of chemically accurate binding energies. We propose an origin of the observed behavior based on a “two state” desorption model.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.