Low-dimensionality effects in the melting of a Langmuir-Blodgett multilayer.
Low-dimensionality effects in the melting behavior of a cadmium arachidate Langmuir-Blodgett multilayer have been studied. Depth resolved information about structural changes occurring with temperature is obtained using in-plane X-ray diffraction under standing wave conditions. The surface region exhibits a distinctly different melting behavior as compared to the bulk of the film. While in the bulk of a 13-monolayer cadmium arachidate multilayer, the crystalline phase directly transforms to a tilted hexaticlike phase at 360 K, in the near surface region transformation occurs via an intermediate smectic phase. This behavior of the surface region is similar to that observed in two-dimensional crystals. Thus even in a thick Langmuir-Blodgett multilayer, the surface region exhibits low-dimensionality effects.
UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452017, India. agupta@csr.ernet.in
Ajay
A
Gupta
Parasmani
P
Rajput
Sigrid
S
Bernstorff
Heinz
H
Amenitsch
D044366:Transition Temperature; D014961:X-Ray Diffraction