Daschbach John L, Kim Jooho, Ayotte Patrick, Smith R Scott, Kay Bruce D
Environmental Molecular Sciences Laboratory and Fundamental Science Division, Pacific Northwest National Laboratory, P.O. Box 999, Mail Stop K8-88, Richland, Washington 99352, USA.
J Phys Chem B. 2005 Aug 18;109(32):15506-14. doi: 10.1021/jp058139p.
The adsorption and desorption of HCl on Pt(111) is investigated by temperature programmed desorption, infrared reflection absorption spectroscopy, and low energy electron diffraction. Five peaks are identified in the desorption spectra prior to the onset of multilayer desorption. At low coverage ( < 0.25 monolayers (ML)), desorption peaks at approximately 135 and 200 K are observed and assigned to recombinative desorption of dissociated HCl. At higher coverages, desorption peaks at 70, 77, and 84 K are observed. These peaks are assigned to the desorption of molecularly adsorbed HCl. The infrared spectra are in agreement with these assignments and show that HCl deposited at 20 K is amorphous but crystallizes when heated above 60 K. Kinetic analysis of the desorption spectra reveals a strong repulsive coverage dependence for the desorption energy of the low coverage features ( < 0.25 ML). The diffraction data indicate that at low temperature the adsorbed HCl clusters into ordered islands with a (3 x 3) structure and a local coverage of 4/9 with respect to the Pt(111) substrate.
通过程序升温脱附、红外反射吸收光谱和低能电子衍射研究了HCl在Pt(111)上的吸附和解吸。在多层脱附开始之前，在脱附光谱中识别出五个峰。在低覆盖度（<0.25单层(ML)）下，观察到约135和200K处的脱附峰，并将其归因于离解HCl的复合脱附。在较高覆盖度下，观察到70、77和84K处的脱附峰。这些峰归因于分子吸附HCl的脱附。红外光谱与这些归属一致，表明在20K沉积的HCl是无定形的，但在加热到60K以上时会结晶。对脱附光谱的动力学分析表明，低覆盖度特征（<0.25ML）的脱附能量对覆盖度有很强的排斥依赖性。衍射数据表明，在低温下，吸附的HCl聚集成具有(3×3)结构且相对于Pt(111)衬底局部覆盖度为4/9的有序岛。
