Variation in anisotropic dispersion relations of self-assembled monolayer on Cu(001) induced by modulation of molecular structures

The two-dimensional electron gas (2DEG) states formed by self-assembled monolayers (SAM) of β-alanine molecules on a Cu(001) surface showed anisotropic dispersion relations different from those formed by glycine SAM. β-Alanine has a structure with an additional methylene group compared with glycine, and enantiomeric isomers were formed through adsorption, similarly to glycine. The anisotropic ratio of the effective masses was changed from 10 for glycine to 3.6 for β-alanine, suggesting the possibility of manipulating electronic structures by modification of the molecular structures. Although the growth modes were different for β-alanine and glycine, 2DEG states with standing waves were observed only for the p(2 × 4) phase in both cases, suggesting a key role of the interactions in the arrangement of this phase, together with the importance of the enantiomeric isomers formed through adsorption, which is also a characteristic of both molecules.