INVESTIGADORES
CALVO Ernesto Julio
artículos
Título:
Molecular orientation in self-assembled multilayers measured by Second Harmonic generation using femtosecond pulses
Autor/es:
CATALINA VON BILDERLING; MARIO TAGLIAZUCCHI; ERNESTO J. CALVO; ANDREA V. BRAGAS
Revista:
OPTICS EXPRESS
Editorial:
Optical Society of America
Referencias:
Lugar: Washington DC; Año: 2009 vol. 17 p. 10642 - 10647
ISSN:
1094-4087
Resumen:
We present measurements of the optical second-harmonic
generation in self assembled multilayer films of PAZO/PAH polymers with
the aim to investigate molecular order in the layer-by-layer architecture. The
experiments are performed in transmission, using a femtosecond Ti:Sa
pulsed laser, which allows a more accurate determination of the amplitude
of the second harmonic signal, without interference fringes usually present
in nanosecond experiments. We found that the first bilayer, in contact with
the substrate, presents a broad distribution of the orientation of the
molecules, while the addition of successive bilayers (up to 12) produces
ordering of the molecules with a small tilt angle respect to the surface
normal. This result, together with the monotonic increment of the second
harmonic signal with the number of layers indicates that the molecules
grow orderly assembled in these films