Phonons
in hybrid lamellar supercrystals are investigated by Raman
scattering. Special attention is paid to low-frequency vibrations
as a mean to shed some light onto the structure at the nanometer scale.
In particular, little is known about the structure of the organic
capping agents in supercrystals made of colloidal nanopoarticles.
This is due to the fact that characterization tools such as electron
microscopy and X-ray diffraction are mostly sensitive to the inorganic
phase due to its larger electronic density. Raman scattering does
not suffer from this limitation. In this class of materials, synthesized
following the “benzyl alcohol route”, the inorganic
layers are kept together by π–π conjugated interactions. Low-frequency Raman spectra have been measured for yttrium
and neodymium oxide-based lamellar organic–inorganic supercrystals
synthesized with three benzyl alcohol derivatives. The spectra strongly
depend on the nature of both the inorganic and organic phase despite
the resulting lamellar structure being similar in terms of layer thickness
and crystalline structure for all the samples. This makes low-frequency Raman spectroscopy the tool of choice for
the study of the assembling process driving the formation of colloidal
supercrystals.