All right first of all want to thank our
border and the people in this wonderful
event and of course for
inviting me to participate in I'm going to
tell you how we can control the joy
metric symmetry of nano particles
in this in this nano particles
can have a very interesting
optical process and the catalytic
a prop this and they can also serve.
Actually if you want to study how
this assemble in different ways and
the symmetry breaking is a very
common phenomena and the symmetry of.
Example over here that Pio is
supposed to have is circular symmetry
if symmetry is broken you know what's
going on right you're going to have you
have basically have had that pile so
you're going to get in trouble so
you affect symmetry
breaking is also volved
at the very beginning of life
development so in this case.
For a story to be secret out and
in this process typically
they are surrounded by and
they are of a different type of
Self's form this a highly symmetrical
structure it's a concentric structure and
at a certain point as free
the symmetry this symmetry is going to be
broken this is through the See question
of some fluid actually form some of
the all of them so basically you only
have a fruit come out from this side of
these cells and eventually will push And
finally this is going to be able
to come out of the air OK So
that's basically the symmetry for you
can involved in that event over life and
here is also quite a common experience you
might have had right where you sit over
here at this table it's so symmetric you
feel confused left side by side which is.
Going to pick up.
The symmetry were broken automatically
someone else callously pick up the classes
from the left side all right side
then everybody knows which side to
use the right so that's basically this
kind of symmetry can typically a way or
code spontaneously and
a randomly and ones that occurs
once that has occurred this kind of
pattern probably can be preserved.
In the conditions of being changed if you
keep the same conditioning the symmetry
definitely could be continued
somebody made it so
let me tell you how we get started
on this kind of problem that was about a
like a ten years ago one all my students.
Was doing this and this this of zero one
nano cubes and on the right conditions
with the help of some polymer in this
particular case is a polyvinyl production
is appalling what they combine to
the one those surface of silver so
basically you can form these coops
as a result for some reason she
didn't obviously the products
immediately she just keep but there's
particles in the solution for Libya longer
maybe like a one hour on longer and
then she somehow inject more
precursors into this solution and
she probably was trying to see if
she can get larger and cubes or
maybe this cubes can grow into octahedron
if you don't have adequate P.V.P.
to passively didn't want to anyway so the
Chiffons I'm seeing a very strange entry
in the shape of these products essentially
complete different from what we would
expect and for most students are probably
about just throw away this them post and
start the nuisances again unfortunately
she didn't look at this very
carefully and then we realize that this
is a very interesting particle and
that it was basically a form of.
No seats in this particular case
however the Crowes was not uniform
on all six side faces basically
a surreal done well somehow turn done.
Done and the other surreal will be able
to grow so you eventually this particular
shopper ten is something we call
semi truncated octahedron S.
So you magic octahedron you truncate
the story of the six corners that's read
it in the grow basically OK and eventually
your pin this kind of structure and
this structure can sit on the surface and
when you did you had to prepare Sampa
they basically can take these two
different patients depend how to sit on
the surface one is against this and
one on one surface look a like a triangle
projection on the T.M. So
that's basically those guys over here and
the same time they missed it only they
missed it against this one no surface so
that will give us the different approach
actually it's like a house because his
house projection So that's basically
the other arm population of this come
apart because so basically this particular
may look a very annoying uniform but
actually it's very uniform
is just the shape it's of.
An arc to hit on shape so
this gave us the starting point to so
we have one to really study to see how
we can control the geometry shape and
the symmetry of this on the particles and
this also of course gave us a hint see
that media across might be a very good
example you can make of the seed which is
one particular size and shape and then add
a more precursor to see how the symmetry
where be changed in the gross process so
that gave us to me two rows approach that
also has been widely used in industry for
example we have to rely on
Silicon Valley for us to make chips and
those silicon their single nanocrystals
actually well pour out from a mail out
various tiny seed at the very tip
of the beginning OK And then the.
And the big OK in this way and
all of this concept
we can just a run in the social face so
you magine you can have a solution over
here you have seats suspended and that you
introduce precursors you can introduce
because at the specific away you want for
example in a kind of concentration
you have for this precursor and
the pace at which you introduce this
precursor and of course this person can be
reduced at a certain radius you have the
right of reducing it in your system anyhow
this newly formed Adams added
onto the surface of seeds and
typically we would expect
that to have some symmetry.
Preserved in this process so for
example this cubic a seed can
grow our lawn that calmness and
the edges eventually develop this and
the symmetrical structure because as
Coffin structures so that's of course
the symmetric process so at same time
you can also Obs open the symmetry for
us why is that why you think about this
see these are two dimensional model
OK you think of this side a face
you have four side the phase and
the Four Corners OK this four corners or
four side effects is equivalent to
each other in a sense OK you cannot do
the really differentiate between them so
now when you add Adams for their surface
OK you can add Adams to all of them
that was key but the symmetry of
the origin the seat on the other hand
somehow if the Adams you
generate in a system not
adequate to be added on to all of these
off or you could have been the corners
you may have this pattern develop this in
this case symmetry where be reduced or
broken up and this particular case so as
a result of that you're going to generate
the structure you know which is
the same symmetry as the seed or
is that given the symmetry so this it
would be awesome if your broken situation
you can also have a different
the patents this is a one way.
You can also have just a rose couldn't
from two of the four corners or
one of them in a cell and so forth so this
about gave us different final products of
course and last year we were published
a short perspective advocate in chemical
communication actually if you're
interested I can take a look at it so
basically this is a cubic seed in this
particular exam but we show we can have
the same symmetry to form a cautious
structure you just deposited new Adams
a run the entire surface of the seat
you're going to generate this symmetrical
structure or you can does deposit
the Adams onto one of the side of
faces generally that a generous particle
you have these two different materials
next to each other side by side now would
be basically a generous particle so
hard to really control and this is so
that's basically the question right so
I try not to be a novice so difficult
OK I just want to point out in the.
Many chemists in the audience this is
a single arm you have this seed so
I'll give when the ears are worse
you can really control the hominy
Adams are going to be generated
in your system if that number but
yours is lower than the equal to
side on the surface of the seat and
the symmetry of probably would be reduced
automatically in the specific a pad So for
example if we only have Sri Adam's
being generated if we tried to
deposit them onto the six side the faces
of these key because seed What can you do
you can only probably reach out to three
of them not all six of them OK but
of course this three can also be dumped
onto one of the side of faces or
two of them at the most surreal of them so
yes since the symmetry has to be
reduced the cost unless you
generate that large and
numb a large enough number all of this
Adams that can be deposited on to
all these different aside if then you can
preserve the symmetry you can have form so
you can have close to generate
a cautious structureless So
basically if there isn't a control over.
Different numbers of Adam's
relative has a number of seeds or
are the number of equivalent sides on the
surface of seeds and then you can control
the pattern is a symmetrical and
symmetric and in this case could be
grown from one of the side to faces
that generate this generous particle and
could be on all six sided face to
generate this cautious structure and
all maybe just on three of the six sided
faces generated is of course our structure
above this is not a going to be
concentric OK this is the seed be located
at one of the corners to form these and
symmetrical structures and
although this can be easily controlled
to use in syringe pump it just drip
This produces through washings at a
specific ingestion rate and you can change
the pace between the droplets and then you
will be able to control your pet it so
here just show you the example you have
grows from one of the side effects this
of these Palladium could be a seed and
what you deposit over here you see over so
you can see it when you add
a more more silver precursors
you are going to obvious of a larger
volume of silver been deposited but
they are only going to be deposited
on one of the side if it is so
there is zero world volume can be
increased but not the going to be moved
to other side if they are localized
to want a particular type so
that's why I'm in the symmetry break
can patent could be intent if we
can experiment the conditions are fixed
and this situation you're going to have.
A run the entire surface of
palladium seeds and you're going to
generate ideas cautious structures and
this is a situation you have.
Three of the sick inside a faceless
you're going to generate this
structure you can see this
in more clearly is so
that's why we use to define the matter so
you can do elemental mapping afterwards so
this is a situation you have
the Palladium next to each idea forming.
And this is concentric.
Structure and this is a one way is the
seeds located at one of the corner sites
OK So that's basically where we
are well defined saying fragged by for
the fine tuning this ingestion
scheme you can generate over on
one of the side faces two three four five
and six all of these different schemes as
well possible if interested take a look at
these people have popped a while ago and
then we'll try to understand
you can do some home to do
control OK basically under what
the specific injection rate and
concentration you're going to generate the
specific pattern of symmetry breaking so
in this case with data some analysis
on the reduction kinetics on the.
And that is kind of simple you think about
this is seed suspended over here you have
a solution be injected and
with specific a pace and its drop
have the same concentration of precursor
So that's kind of simple and for the first
the drop you add into the solution that
will be reduced by the reducing agent
to have this in the system but
generate the atoms for the gross right so
you see the concentration of
wealth decrease because of the.
High ever before all of this precursor
reduced to the zero you have the second
the drop come into the system so
that's basically where you have the second
the drop been added and the concentration
on cost of a jump OK and then you're going
to have reduction again and again and
assume so force so that basically
refracts How does concentration
in a system change as
a function of reaction time and
this is very similar to the situation when
you take a medicine every day if you take
one every day eventually in your body you
are going to have previous day becomes
infusion of the Medicine at three this
is similarly shown over here basically
the concentration of precursor in
the system eventually will be also waiting
between two numbers one is a new low
one is in a tree that refreshes the.
And the high concentration
you can achieve.
Of these precursor social and
easy to calculate is OK if you know they
need your concentration or precursor in
the with the actual rate of this precursor
by that particular reducing agent and
taught over here years just the duration
between two and if yes in the droplets and
once in though there's numbers you would
be able to calculate basically you can see
when you change those define
the parameters you can have different and
and low this to differ and are basically
limits for the concentrations and
then we end the lies the pot of course
we are going to observed after a certain
period of time and you can analyze how
many of them are going to be symmetrical
and symmetric symmetric and symmetric so
we fund that basically under certain
conditions this condition years
of when this Anglo is larger than
eight some hundreds eight OK we haven't
been able to understand why it's eight and
in this region you are going to have
majority of the product has been and
symmetric symmetry somehow is broken and
when a load is
smaller than eight basically you're going
to generate symmetrical structures OK So
basically have rows on all the side of
faces and then we start to understand.
What that we can propose while when
you put this Adams onto the surface at
the very beginning as I said it has
limited by the available number
of ADAMS The symmetry is supposed to
be broken OK at the very beginning
high above this.
Pattern also.
Tend to do it in the afterwards.
Process and this is the other two
reasons one is this Adams could be able
to migrate to other areas if temperature
is high enough OK they don't have to
be localized to this initial
site if they can diffuse
to other areas so symmetry be preserved
you're going to achieve symmetric.
Rose and I same time if you have
too many precursors have been added
They may also have edition a new
creation on the size so basic and
that has to mature way of the also
preserve So basically they've gave us some
a semi quantitative understanding under
which conditions you're going to generate
this and symmetrical or symmetrical just
two different categories of nano particles
of course the rest you're trying to do
more systematic study to figure out in
on the use that of which condition
you're going to generate a specific at
a particular symmetry OK and
this symmetry with actually operate
can phenomena is kind of universal OK We
just didn't pay much attention to this so
here is them to show you another example
of how we can generate up to he draw and
the tetrahedra there's two
related to nano Christus
there Sophia's Abos cover the VI one
on one OK but they have different
volume to surface area ratios of cause
this symmetry is very different so
in this case the wrist other ways of
the heat of seed and initial stage
both of them will be able to generate
octahedron using different precursors and
then suddenly for
this type of precursor P.D.
economic and
that the symmetry would be reduced so
basically you think about these up the
heater you have some eight sided faces and
if all of these four can grow you can make
a larger up the heat high of why you have
four of them OK you can only have gross
alone for the rest of all of them and
eventually they are going to generate this
tetrahedron So you have see this kind of
without wishing in terms of symmetry and
this turned out to be related again to
the kinetics of the without wishing for
the precursors one of them was
reduced the relatively slowly you have
this little reduction for this case but
this one you have very quickly and
the reason you how quickly the action they
have simply read that she knew it was that
was their concentration became very low
and then the Adams vailable for
rose suddenly is going to be.
Lower than you quiver
the sides on the seat so
that's why only half of this sixty eight
side if it would be able to grow and
the other four would be just automatic
shutdown generated this particular So
here's another example that's also
interesting in this case the wrist
the other way is that behavior
of seats are shown over here and
we're shown a long time ago you can have a
way to elongate alone the actual direction
of this seat and eventually you can
generate these so-called to wind.
Noise that could be useful
form an applications and
then a few years ago when we look at this
problem again with other ways of different
type of seats we use the Palladium seats
instead of using silver seal was terrible
you don't know you are symmetry was a pro
can OK you cannot really tell you cannot
do mapping and figure out of the symmetry
by the one with switch to Palladium seeds
and also switch to a different
the precursor this is going to be
reduced pretty slowly on that they
spend the conditions we use and
then afterwards when we
analyze this nano rods or
nano wires if longer and refund something
interesting basically this seed
is a good to be located at one of the two
ends it's not in the middle point
OK of these rods it's always going to be
located the one on the ends of course so
again it didn't this process the symmetry
was broken it's not a corner from both
sides just a skull with one of the two
sites and stem is also true for
another system when we use
Palladium seeds and the grower for
the gross of copper archery Finally for
this and the rot and
we are protesting that the seeds again
is going to be located on one of the two
ends not in the middle OK so
it's symmetry was against him it was
a broken down in this kind of process so
here is the most recent example OK here's
another way or another type of symmetry.
Or symmetry a bridge in this
is kind of a structure with.
This is kind of like
a horror show interior and
that in the Soviet saga Sophie's is
going to be symmetrical to each other in
principle even though the environment
a might be slightly different right
by the overall use thing that
is going to be a symmetry and
the one with deposit or
some more Adams onto this particular
you can have deposition on the outer
surface only or maybe on the outer and
in the surface so again this is a going to
be a more or less like a symmetrical rose.
Out in the face and this is going only
have grows on the outer So based.
On the in the surface the symmetry was
broken in this case so the question is can
we really control and to generated this
type of structures selectively OK and
turned out to be possible again we look at
the reduction kinetics if the precursor
can be reduced very quickly into Adams and
this Adam's tend not to be only deposit
on the outer So they have no chance to
diffuse into the interior because once
the atom get through very close to the
surface bone dry are going to be deposited
on the surface unless this precursor
cannot be reduced very slowly and
they can have a chance that they fuse
into inside of this hollow structure and
then being deposited and
in this case the outer side in the side is
a going to be more or less equal to each
other so you can preserve the scimitar So
it's a kind of like a you need slow
reduction again faster with action in this
case that I'm sorry and then you're going
to be able to preserve the symmetry if you
have a faster without wishing you're going
to just get the symmetry in this case so
we'll use this go on OK just to do this
experiment for one of them where use this
precursor of the impetuous call right that
can be reduced to read three quickly and
then we have another arm come to a pot
that's a political head to a brawl might
be reduce the slowly and
then after deposition we can analyze
the change of dimension that in
the channel check what the management.
And out to the dimension of this and then
a cage and then here is the prologue this
green bar shows you the thinking
this of the wall for
the all region the Nano cages and then
this is a brew one is the thinking this of
metal you deposit on the altar so face and
this is red a second one indicates
the matter you deposit on the inner
surface and in this case it's going to be
symmetry broken OK you only have
deposition on the outer surface but
this is one for this precursor it's
a slowly reduce you won't be able to
generate the symmetric on the outer and
in the surface OK so you can see again
very clearly here as on the rest T.M.
You can see this is a symmetrical
structure you have gold in the middle you
have Palladium on the outer and inner So
face but in this situation you are going
to have put it on the outer surface only
very little on the in the surface so
again you can see the symmetry could
be preserved all broken OK depends on the
experiment the conditions in this case is
I'm in the reduction kinetics of
the system so what I have shown your so
far mainly based on what having a systems
so you can fragment even before we look at
this system we also look at the hybrid
systems in this case we have
a polymer being deposited on
the metallic nanoparticles seeds and
to form this carload the sphere us and
we find that doing the part of
OS tiring to make the poorest are in beads
at a certain point after the initial.
Thought of choroid and
we find that this porous star
eventually can only be nucleated
form a small patch regions and
thought a surface it's not going to be on
the entire surface of the boat and this
part is starting again can be increased in
terms of volume as proceeds and eventually
it will form this kind of interesting
structure of the seed that go to seed is
a going to be sit at one side of this in
the other going to be in the center OK.
And here to show you some T.M. images you
can different sized goal nanoparticles you
can see you have this gold
located in the center
of the particular alright and here
are some more examples of all this and
this is based on the solution phrase our
procedure so that means you can make
a logical in that it doesn't there
are really no limitations and
this is basically a back scatter S.C.M.
scanning electron microscopy which So
you can see the it's particle Where
have a code inside by the not in
the center is it going to be opposed to
the edge and here you can see this part of
the actuary is not exactly inside
of the porous downbeats is just
slightly imbedded into the surface of this
particular So that indicates there is.
A sun at night as you were
given some of this particular.
Tree for study and how this particular
way I assembled because this particular
shown over here could be called the
platinum palladium they have had a little
properties so you can trigger how they
are going to move when we add a sum for
us in the system anyways the interest of
them so finally let me show you another
example this is like a you make in part
because with some more poor tree in the SO
face again it's not a symmetric it again
right is not in the script of symmetry and
then more and to make of them is also
simple you took some lively cross link it.
Beats with swelling and
with solvent the like appalling So
make a larger particular and
then we freeze dry it and
then we landed this is solvent
evaporates on the vacuum conditions and
automatically again they change
their symmetry to this point it's
like a streak of symmetry OK but when we
have your valve which is like a volcano
you have proceeding in the symmetry
is automatically broken again so
you're going to generate
a small hole on the surface and
to form this kind of particular And
here just show you some examples again of.
It is another go to particular this
is small boy this is estimates
not the T M A M H T M image and also once
you have formed there is no particular
you can lead this small hole
to be closed if he did that.
All close to a deposit on the temperature
of the polymer So they're going to
basically start to close up and eventually
about Chris of a come completely OK but
in this way you can control the size
of the opening OK And also the voids
inside there's a particular and
interested you can lower
the inside with something in this case
could be sodium chloride a solution and
then you lead them Crystal out OK form
this a little pot it goes inside and
once is complete the crows how to go
supposed to have over all the symmetry but
if you look at the interior structure
is not the screw the symmetry OK
it's going to be given the symmetry OK A
You can also have liquid to be included.
Eventually become sorry the particles
in this case could be just the PO for
a column this kind of liquids depend
on how much you edit you can also have
different degrees of feeling and you
also have a some interest in particle B.
This kind of interesting overall spherical
symmetry but in detail it's not so
symmetrical in a sense so
I hope I gave you some examples OK how
we can manipulate also ensure the symmetry
of nano particles in their fabrication
awesome this is a process and the fault
metallic nanoparticles basically.
Like a criteria you had to observe
first you had to make sure you only
have he did units nucleation and
this Adams only nuclear on the surface of
the seeds otherwise you're going to do
have a homogeneous nucleation it's
going to be out of control and
when you can only have he did in his new
creation you can control the number of
Adam's been generated basically you
can control hum in this side of.
Of will be involved in the new
creation the crows and
then in that case the symmetry
can be reduced to or
broken at the end the specific
a pattern you want to have and
of course you have today made the surface
deficient you can imagine even you have
a symmetry breaking in the new critical
stage with this Adam combined with freely
easily on the surface of course they
would like to populate the other side so
the symmetry would be preserved
instead of being broken so
basically all you probably need to keep
the temperature obvious and this is
relatively low to minimize the surface
deficient of atoms but in a way I hope.
You have some interest in this particular
if you find any use you can send me emails
more than happy to send you
some sample to study and
find that it doesn't run to
the knowledge of funding agencies.
Of course this funds play
a very important role in my
career there have been over
the past ten to yes and
that's why attention to having
to answer questions thank you.