  We present a combined x-ray diffraction and infrared spectroscopy study on
the phase behavior and molecular dynamics of n-hexadecanol in its bulk state
and confined in an array of aligned nanochannels of 8 nm diameter in mesoporous
silicon. Under confinement the transition temperatures between the liquid, the
rotator RII and the crystalline C phase are lowered by approximately 20K. While
bulk n-hexadecanol exhibits at low temperatures a polycrystalline mixture of
orthorhombic beta- and monoclinic gamma-forms, geometrical confinement favors
the more simple beta-form: only crystallites are formed, where the chain axis
are parallel to the layer normal. However, the gamma-form, in which the chain
axis are tilted with respect to the layer normal, is entirely suppressed. The
beta-crystallites form bi-layers, that are not randomly orientated in the
pores. The molecules are arranged with their long axis perpendicular to the
long channel axis. With regard to the molecular dynamics, we were able to show
that confinement does not affect the inner-molecular dynamics of the CH_2
scissor vibration and to evaluate the inter-molecular force constants in the C
phase.
