Vibrational/HREELS, UV/HREELS, and temperature-programmed desorption of benzene and hydrogen on (2×1)Pt(1 1 0)

In the previous literature, there has been controversy about the nature of adsorbed benzene on platinum. Some workers say that the benzene is undistorted upon adsorption, while others say it is highly distorted. s paper, the interaction of benzene with (2×1)Pt(1 1 0) was studied with vibrational/HREELS, UV/EELS, and temperature-programmed desorption. It is found that two different forms of benzene can be formed upon adsorption on Pt(1 1 0): an undistorted form and a highly distorted form. The distorted form is produced at low coverages and has a HREELS and UV/EELS structure consistent with that for a dienyl species. The high coverage has a spectrum which matches the expected spectrum for benzene. Temperature-programmed desorption shows that the distorted form mostly decomposes to carbon and hydrogen upon heating, with a fraction desorbing. In contrast, the molecular form simply desorbs upon heating. The distorted form can also be hydrogenated to cyclohexene while the undistorted form is unreactive. ork provides clear evidence that two different forms of benzene can be produced on Pt(1 1 0), which explains why different investigators have come to different conclusions about the nature of adsorbed benzene.