Transcript Nanoparticle Generation

Core-Shell Nanoparticle
Generation
Using Laser Ablation
Vanessa Coronado, Westside High School, Houston ISD
Dr. Sy-Bor Wen/ Assistant Professor and
YoungKyong Jo/ Ph.D. student
Dept. of Mechanical Engineering
http://www.istm.cnr.it/~ponti/NJC06.html
Dr. Sy-Bor Wen, Department of Mechanical
Engineering
• Ph.D. in Mechanical Engineering
@ University of California at Berkeley, CA
• M.S. and B.S. in Mechanical Engineering
@ National Taiwan University, Taipei, Taiwan
• Working on using lasers to ablate germanium and copper and
condense them together to form a nanoparticle core-shell material
that has superior optical and electromagnetic properties.
Ablation: \a-’blā-shən\
• Using a laser to vaporize material.
What is nano?
• Very small!
• 1nm, is a nanometer = 10-9m.
• Essentially, a billionth.
• It takes up to 150,000 nanoparticles to be
as wide as a human hair.
Lasers being used
• Excimer laser – class IV laser
(short for 'excited dimer‘)
193 nm = UV light
• Nd: YAG laser – class IV laser
(neodymium-doped yttrium aluminum garnet)
532 nm= green light
en.wikipedia.org/wiki/Nd-YAG_laser
• The laser light is fed through a series of
mirrors and lenses to a closed chamber
that has the samples of copper and
germanium inside.
Two pulsed laser ablation
*Sample alignment
Nd:YAG laser
*Copper Fiber
0.25 mm
Excimer Laser
*Optical Fiber
*different materials used in current lab set-up.
•
Courtesy of YoungKyong Jo
Courtesy of YoungKyong Jo
• The excimer laser is triggered first to ablate the
germanium and a fraction of a second later the
Nd: YAG laser will be triggered to ablate the
copper sample.
• A plume of
germanium is first
created then the
copper is ablated to
create a larger
second plume that
will condense onto
the first.
Courtesy of YoungKyong Jo
• This is all captured
by an ICCD camera.
An ICCD camera
captures light as
sensitive as a single
photon….much better
than my camera…
http://www.canemco.com/catalog/grids/Quantifoils.htm
http://www.gatan.com/resources/answers/Answer-10.php
• Once the particles have condensed
and formed, they deposit on the
inside of the chamber onto a
collection plate strategically placed
inside of the chamber. This occurs
over a period of time that varies up to
2 hours.
transmission electron microscope
scanning electron microscopy
http://www.nims.go.jp/htm21/MA/tem.jpg
• The particles are then taken for imaging using
a SEM- scanning electron microscope and a
TEM- transmission electron microscope to see
if core-shell nanoparticles were created.
Possible applications of
nanoparticles
• Biomedical uses – cancer cell eradication
that targets only malignant cells
• Better catalyst
• Creates stronger magnetic field for use in
electronics
• Makes stronger, lighter composite
materials
• ? ….we don’t know what else….
Variables being tested
• the position within the chamber
that the sample is being collected
from.
• the gas that is within the chamber
is variably argon or helium.
in air
in argon
Variables being tested
• the time that the sample
deposits on the collection
grid
• the time between the lasers
being triggered
Variables being tested
• the laser energy
being used
• the amount of gas
flowing into the
chamber
What are we doing?
•Learning about experiment
•Studying procedures
•Running experiments
using different variables
In summary….
• 2 lasers ablate germanium and copper a
fraction of a second apart
• Second material condenses onto first to
form core-shell particle
• Particles deposit over time and are sent to
a SEM and/or a TEM
• If the particle is a core-shell
particle…party…. then determine the
properties of it.
How will this translate to the
physics classroom?
Not sure yet…but somewhere along the
lines of…(get it…it’s a little laser joke)…
• Supporting TEK 8: “The student knows the
characteristics and behavior of waves.”
and/or
• Supporting TEK 9b: “the student is
expected to explain the line spectra from
different gas-discharge tubes.”
What might this look like?
• Using classroom grade lasers coupled
with mirrors and lenses to discover
properties of light and waves
• Use spectrum tubes to discover the
differences between colors of light and
what makes them unique.
http://webapps.lsa.umich.edu/physics/demolab/controls/ima
gedemosm.aspx?picid=600
Acknowledgements
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Texas A&M
National Science Foundation
E3 RET Program coordinators
Mechanical Engineering Dept
Dr Sy-Bor Wen and his team
And viewers like you
Any questions?