Page 26 - CFM_Newsletter_CY22

mechanisms of fiber optic plasmonic sensors with different geometrical structures and the photonic
properties of the geometries enhance the sensitivity of the sensors. The studies of optical properties with
a combination of suitable materials for testing the biosamples allow for diagnosing diseases in the medical
field.

Twisting Curved л Aromatics
th
Dr. Senthil Kumar Kabali, Marie Curie Postdoctoral Fellow-University of Durham, United Kingdom, August 29
Conjugated macrocycles have
attracted considerable attention
due to their unique electronic
and optical properties, which
make them interesting
candidates for application in
molecular and organic
electronic devices or
photoswitches. The [fn]cycloparaphenylenes
([n]CPPs), macrocycles built from benzene rings linked at the para positions end-to-end, illustrate the
challenges faced when targeting highly strained molecules. A cycloparaphenylene-based molecular
lemniscate (CPPL), the lenticular analogue of [16]cycloparaphenylene was synthesized of a radially
conjugated z-electron system with a double half-twist. The structural design of the cPPL provides a unique
opportunity to observe the effect of curvature variations on the electronic structure in isolation from other
influences. The electronic properties of this new system differ from those of the parent [16]CPP ring,
showing absorption and emission features more characteristic of smaller cycloparaphenylenes. The
twisted nanohoop of CPPL can be resolved into configurationally stable enantiomers, which are found to
produce circularly polarized luminescence (CPL). More generally, the approach to curvature control
presented in this work enables the reduction of electronic bandgaps while retaining large conjugation
lengths in nanohoop systems. Also, Raman optical activity and circularly polarized luminescence have
been detected, in a single Raman experiment, for enantiomers of a cPPL stabilized by a bicarbazole unit.

ZnO nanowire growth by using thermal oxidation process
Mr. Sri Aurobindo Panda, Project Fellow, Nano Science Lab, Department of Physics, BITS Pilani, Pilani campus, Rajasthan, India,
th
October 28
Thin films of Zinc were grown on a
glass substrate followed by thermal
evaporation of pure metallic Zinc in
a vacuum (Pressure=10-5mbar).
The structural studies of the films
were carried by X-ray diffraction
(XRD) technique which pattern
shows the hexagonal Zn structure
for deposited thin films. The XRD
patterns of Zn films turn into wurtzite ZnO structure at
the oxidation temperature between 400⁰C to 600⁰C for 4 h. The morphological studies of the films were
carried out by the FESEM characterization technique. SEM images confirmed the hexagonal shaped
grains for deposited Zn thin film that turns to 1D-nanowire with the heat treatment which show the
asymmetric growth of ZnO above 500 ⁰C. The chemical composition of the ZnO films was studied using
Raman spectroscopy which complements the XRD result. These ZnO nanowires would be a potential
candidate for various gas/vapour sensors, due to their extremely high surface to volume ratio.

CFM Newsletter Jan. – Dec. 2022 26 Vol – 2