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Application Paper Spotlight on Carbon Nanotube Growth Mechanisms

23 April 2015

 Carbon Nanotube Growth Mechanisms

Quantum Composers 9520 Series Digital Delay Pulse Generator has been featured in an applciation paper from École Centrale Paris: "In situ diagnostics for the study of carbon nanotube growth mechanism by floating catalyst chemical vapor deposition for advanced composite applications."

Abstract

In the vast field of nanoscience and nanotechnology, carbon nanotubes
(CNTs) are of particular interest because of their unique
structure which provides them outstanding properties. While the
number of CNT-based applications as well as the amount of CNTs
produced are increasing year by year, it is essential to understand
the mechanisms governing the formation of these nanomaterials to
control their structure and organization, maximize the yields, reduce
the health and environmental risks and improve the performance of
the underlying materials and components. Among the listed synthesis
techniques, the aerosol-assisted chemical vapor deposition (CVD)
process developed in the laboratory MSSMat allows continuous growth
of multi-walled CNTs (MWNTs) on various substrates by the simultaneous
injection of carbon feedstock(s) (xylene and/or acetylene) and
catalytic precursor (ferrocene) in a reactor heated up to a temperature
ranging between 400 and 1000➦C...

...Experimental procedure
In the same way as TRLII, an aperture (about 1.5 cm in height)
was designed at the center of the high-temperature furnace without
changing its temperature profile. A 10 Hz first harmonic laser beam
(1064 nm) initiated by a Nd:YAG laser (Surelite II-10) was focused
(f = 150 mm) at different positions on the quartz plate used as a
substrate during the CNT synthesis by CVD. An energy meter was
set up to control the laser fluence. The laser energy was about 500 mJ
per shot before focalisation. The backscatterred signal was collected
by a lens (f = 250 mm) directly to a spectrometer (CCS Thorlabs
200) for further analysis in the range between 200 and 900 nm. The
acquisitions lasted for 10 ms and were synchronized with the laser
pulse using a delay generator (Quantum Composers 9520 Series).
Moreover, the effect of the angle between the incident laser beam
and the substrate on the LIBS signal intensity was studied, while the
detection position was kept constant. This factor shows a significant
influence on the LIBS signal, as shown in Fig. 2.3.5. The LIBS signal
intensity is maximal when the incident laser beam is normal to the
substrate surface, while it increasingly decreases as the angle differs
from 90➦."

Check out the full paper Here!

 

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