Crystal Structure of Triclinic Form of n-Octadecane

The crystal structure of triclinic form of n -octadecane, C 18 H 38 , was determined. The lattice constants are a =4.361 A , b =4.893 A , c =25.04 A , d 001 =23.055 A , α=83°06', β=67°04', γ=111°24', with one molecule per cell, space group being C i 1 – P 1. Atomic parameters were determined by Fourier method. The results obtained from two projections show that the molecules have a regular and periodic zigzag shape within an experimental error. The diffuseness of atomic peaks near chain ends in Fourier maps is discussed. It was concluded that the origins are possibly the thermal motion of the molecules and an impurity effect.