Self-assembly of C16En molecules on HOPG surface

Adsorption and self-organization of C16En (n = 1 and 3) (mono and triethylene glycol hexadecyl ether) have been studied on HOPG by using scanning tunneling microscopy (STM). Both the molecules form stripe patterns. The angle between the alkyl axis and the molecule row is about 30°. The alkyl chains of C16E molecules can be well resolved. The adsorbed structure has a bend, which forms an angle of about 110°, in the alkyl chain near the head group. The joining section of alkyl chain and head group appears as a bright spot, which is attributed to the conformed transformation of CH2CH2E bond from trans in the crystal to gauche in 2D structure. For C16E3 molecules, we cannot obtain atomic-resolution images.