Abstract

The effect of backbone on the adsorption mechanism of homo-trifunctional molecules on Ge(100)-2 X 1 has been studied. The chemisorption of the triols 1,3,5-benzenetriol and 2-hydroxymethyl-1,3-propanediol on Ge(100)-2 x 1 was investigated by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations. Both triol molecules undergo an O-H dissociation reaction with the Ge dimers, with experiments showing that the fraction of O-H groups that dissociates per molecule is the same for 2-hydroxymethyl-1,3-propanediol and 1,3,5-benzenetriol. Experimental results suggest that for both molecules there is a mix of products formed at saturation, with evidence of trifold adsorbates. The flexibility of the backbone is shown to influence surface coverage and dimer occupancy, with the flexible backbone able to pack the surface more easily. DFT calculations support these results by showing favorable pathways for all reactions through single, double, and triple O-H dissociative products for both molecules along the reaction coordinate. DFT results also show differences in adsorbate-induced strain between both molecular backbones.