Temperature-programmed reaction/desorption, reflection−absorption infrared spectroscopy, and density functional theory calculations have been employed to investigate the adsorption of ClCH2CH2Cl on Cu(100) and O/Cu(100) in the subjects of identification of the rotational isomers, adsorption energy, adsorption geometry, thermal stability of the layer structure, and transformation between the trans and gauche conformers. On Cu(100), both the trans and gauche forms of ClCH2CH2Cl coexist on the surface at a monolayer coverage, and their thermal desorption peak appears at 187 K. The trans molecules are likely adsorbed with the C−Cl bonds approximately parallel to the surface. On O/Cu(100), the gauche conformer is the predominant species and the desorption temperature is shifted to 199 K. It is found that the ClCH2CH2Cl layer structure on Cu(100), up to a ∼15 monolayer coverage studied, is stable between 120∼140 K. However, O/Cu(100) shows an interesting contrast. The thermal stability only appears at a coverage below ∼3 monolayers. The transformation from gauche to trans takes place for higher coverages. On the basis of the cluster-model calculations without consideration of the interaction between adsorbed molecules, it is shown that the activation energy for the transformation between trans and gauche ClCH2CH2Cl on O/Cu(100) is much lower than that on Cu(100), suggesting that the trans molecules are easier to be transformed into gauche ones on O/Cu(100), as they are adsorbed on the proximity of preadsorbed oxygen atoms.

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Articles you may be interested in 1,2-Dibromoethane on Cu(100): Bonding structure and transformation to C2H4 The interaction of atomic hydrogen with the Cu(111) surface was studied by a combined experimental-theoretical approach, using infrared reflection absorption spectroscopy, temperature programmed desorption, and density functional theory (DFT). Adsorption of atomic hydrogen at 160 K is characterized by an anti-absorption mode at 754 cm −1 and a broadband absorption in the IRRA spectra, related to adsorption of hydrogen on threefold hollow surface sites and sub-surface sites, and the appearance of a sharp vibrational band at 1151 cm −1 at high coverage, which is also associated with hydrogen adsorption on the surface. Annealing the hydrogen covered surface up to 200 K results in the disappearance of this vibrational band. Thermal desorption is characterized by a single feature at ∼295 K, with the leading edge at ∼250 K. The disappearance of the sharp Cu-H vibrational band suggests that with increasing temperature the surface hydrogen migrates to sub-surface sites prior to desorption from the surface. The presence of sub-surface hydrogen after annealing to 200 K is further demonstrated by using CO as a surface probe. Changes in the Cu-H vibration intensity are observed when cooling the adsorbed hydrogen at 180 K to 110 K, implying the migration of hydrogen. DFT calculations show that the most stable position for hydrogen adsorption on Cu(111) is on hollow surface sites, but that hydrogen can be trapped in the second sub-surface layer. © 2013 AIP Publishing LLC. [http://dx.