M. Hibino et al., MICROSCOPIC ORIGIN OF THE ODD-EVEN EFFECT IN MONOLAYER OF FATTY-ACIDSFORMED ON A GRAPHITE SURFACE BY SCANNING-TUNNELING-MICROSCOPY, JOURNAL OF PHYSICAL CHEMISTRY B, 102(23), 1998, pp. 4544-4547
Monolayers of saturated fatty acids with various chain lengths were ad
sorbed onto a graphite substrate, then studied using the scanning tunn
eling microscope (STM). The STM images indicate that in the direction
parallel to the molecular axis the molecules form centrosymmetrical di
mers via hydrogen bonds between the carboxyl groups. From the symmetry
of the STM images, it was found that a unit cell of fatty acids with
an even number of carbons is different from that of the odd-numbered s
eries. These phenomena provide evidence for a basic mechanism of the o
dd-even effects in the arrangement of alkyl chains.