Transcript WoodCross-2 - Department of Chemical Engineering

Where Chemistry Can Take You
From the lab to the Stars
From Utah to China, Japan &
Switzerland
by Terry A. Ring, Ph. D.
Bingham High Chemistry
Earning a Living with Chemistry
Talk about some of my research
Making Powders by Crystallization[= Precipitation]
Nucleation
Crystal Growth
Making Nano Particles
Nano Particles = Big Surprises
Demonstration
Clock Reaction
Ring’s Chemistry Competition
Go to College and Get and
Education
Why do your parents keep saying that?
Education Pays
What do you want to be
when you grow up?
Many possibilities to use your scientific
education!
Biologist
Chemist
Physicist
Engineer
YOUR DECISION HAS CONSEQUENCES!
$$$$$$
How Much Do You Want to
Earn When You Grow up?
Job Growth
Chemistry Job Growth rate is ~14%/yr
Do the Popular Professions
Pay Well?
Which Job Pays More?
Computer Engineer?
Biologist?
Chemist?
Chemical Engineer?
Salary Information Chem. Eng.
Median Salary for B.S. =$62,000/yr
Starting Salary ~$54,000/yr
Starting Salary
Crystalization Research
Additives Control of Particle
Shape
Epitaxial Aggregation
Mixing - 1μs to 10 ms
Nucleation - 10μs or mixing time
Growth - 10μs or mixing time
Aggregation - 10 ms
Self Assembly - 10 ms
Hexagonal Packing of
Spheres
Light Diffraction
Defects in Ordered Arrays
Bend Light
Optical Semiconductors
Photonic Crystal Light Pipe
Light Pipe
Light Leaving Pipe
Nano-sized Cluster
Nucleation
Terry A. Ring
Chemical Engineering
University of Utah
Introduction
Classical Nucleation Theory & Limitations
New Theory & Findings
The Nanoscale is small!
Conventional Machines
(m - mm)
Microelectronics (micron = 10-6 m)
(10 cm down to 0.1 µm)
Nanotechnology
nanometer= 10-9 m
(100 nm to 1 nm)
Silicon Particles
Introduction
Unique Properties of Nanosized Particles
Plasmon Resonance -color due to size, color change due
to adsorption-sensors
Between Bulk and Atomic Electrical Properties
Catalytic Properties
Magic Cluster Sizes
C60, C70, C nanotubes,
Na clusters of 8, 20, 40, 58 and 92
Stimulated Emission CdS
Nano-Clusters-Laser
 Lasing only when quantum
dot concentration is
sufficiently high.
 Stimulated emission>Auger
recombination
 Klimov, V. Mikhailovsky,
A.,Xu, S., Hollingswork, J.,
Malko, A., Bawendi, M.,
Eiser, H-J., Leatherhead,
C.A.
 Science 290,314 (2000)
 Science 287,1011 (2000)
Fullerene Synthesis
Not Predicted
By Theory!
Nanoparticle Synthesis = Nucleation
• Classical Nucleation Theory vs New Theory
– Binding Energy per Li atom
Kouteckky, J. and Fantucci, P., Chem. Rev., 86,539-87(1986).
18.3358
(
GS )
is
2
3
2
4 . . a1 .  . ig
kB . T
ig
1
0 . ig
-0
0
1
10
is , ig
20
20
G(i) = - i kBT lnS +  ba ao2 i2/3
Population Balances
Classical Nucleation = Single Atom Addition
Ck / t 
 lij=(i+j),
1
l1,k 1C1Ck 1  l1,k Ck C1
2
Population Balance - Multi-atom Addition
k 1

i 1
i 1
Ck / t  1/ 2 li,k iCiCk i  Ck  li ,k Ci
 lij=(i+j)exp(-DGij/kBT),
Quantum Mech.
1
1
C
m, 1
C
m, 1
N( m. Dt , 1 )
0.5
C
m, 2
N( m. Dt , 1 )
0.5
C
m, 2
N( m. Dt , 2 )
N( m. Dt , 2 )
0
0
1 10
6
2 10
m. Dt
6
6
3 10
0.9999
N
C
Classical
tmax .
Dt , k
2
tmax
,k
2
N( tmax . Dt , k )
C
tmax , k
4.63056e-33
0 1 2 3 4 5 6 7 8 910
k
9
0
1
0.1
0.01
tmax .
0.001
Dt , k
4
2
1 10
5
1 10
6
tmax
1 10
,k
7
1 10
2
8
1 10
( tmax . Dt , k ) 1 10 9
10
1 10
11
tmax , k
1 10
12
1 10
13
1 10
14
1 10
0
0.05
m. Dt
0.1
1
0 1 2 3 4 5 6 7 8 910
k
Population Comparison
New Theory of Nucleation
Overcomes Limitations of Classical
Nucleation Theory
Multi-atom addition
Free Energy driving force for Diffusion and
Addition
Predicts Transients for Cluster Concentration
of Each Size
Qualitative similar to Si Plasma Expts
Collision Energetics
0.8
o
BE/ n (eV)
BE
(i+j)
0.6
o
BE + BE
i
j
²E
Crystallolumines cen ce
0.4
o
EA
BE *+ BE*
i
j
0.2
0
0
2
Collision Trajectory, R/r
Figure 3 Collision trajectory for collision between i=3 and j=4 clusters,
showing ground state energies before and after collision, as well as the
activiation energy of collsion.
4
e
Crystalloluminesent
Spectrum
Intensity vs Energy
Intensity =
0.1
0.01
0.001
collisions/per unit time =
photons/unit time
Wavelength E = hc/l
1 10
1 10
1 10
I
i, k
1 10
1 10
1 10
1 10
1 10
Human eye detection
3x104photons/cm2/s
@
λ 510 nm
at
1 10
1 10
1 10
4
5
6
7
8
9
10
11
12
13
14
0
0.5
1
1.5
DE
i, k
eV
2
2.5
Similar to Line Spectra
Crystalloluminescence
• Term Schoenwald in 1786
30 References 1786 and 1957
• “An understanding of crystalloluminescence in not to
satisfactory at the present time,” E.N. Harvey 1957
Examples:
NaCl, KCl, NaF, AsCl3, K2SO4, As3O3, Sr(NO3)2,, CoSO4, K2CO3, KHSO3, NaKSO4,
NaKCrO4, NaKSeO4, Na2SO4, benzoic acid, and ice, water.
16 References 1957-1991 (15 Russian+ 1 UK + 1 Italian Review)
 “It is not possible to … provide either a unifying physical picture of the microscopic mechanism
governing
(crystalloluminescence)
or
a
physical
rule
that
allows
(identification
conditions...where the phenomenon is stronger,” Barsanti, M. & Maccarrone,,F., 1991
3 References from 1991-2000 (2 India, 1 Russian)
of)
Experimental Observations
 Delay time is a function
of concentration & mixing
Flashes are Short
< 80 ns
Saturated NaCl + Conc. HCl - 120 s observation time
Peak Count rates
~5-8x105 photons/s
Gibbon, M.A., Sopp, H. , Swanson, J., and Walton, A.J., J. Phys. C. 21,1921(1988).
Temporal & Spatial
Bunching of Flashes
340nm<λ<380 nm
Blue White Light
Spectra Has Series of Peaks
Different from
Thermal
Luminescence
Photoluminescence
Impurities in Crystal
have a Big Effect
Spectrum
Rabinerson, A.I. Wladimirskaya, M.A., Acta Physicochimica URSS, 10,859(1939)
Makes New Predictions
Explains the reason for the occurrence of Magic
Clusters and how the change with time.
Method to Quantitatively Measure Nucleation
Events
Predicts Crystalloluminescent Spectrum
Where could we see Crystalloluminescence?
H2O Condensation Nucleation
Interstellar Dust Nucleation
Light from Deep Sea Vents
Water Condensation due to Shock Wave
Interstellar Dust Clouds - Light from the Fringe
- Crystalloluminescence due to Nanocluster Nucleation
Experimental Verification
Nanocluster, Ti14C13
with emission peak at 20.1 microns
is seen in Egg Nebula by
A.G.G.M. Thielens and M.A. Duncan
Science 288,313(2000)
this joins some 120 other small molecules
identified in the vicinity of stars,
interstellar gas and dust clouds
Super Novae
Deep Sea Vents
National Geographic October 2000
C&E News 12/21/98
Deep Sea
Life
Salt Lake Tribune, 2/13/97
National Geographic October 2000
Deep Sea Vents
Deep Sea Vents Spew Solublized Salts into
the cold sea, causing Precipitation &
Crystalloluminescence
In the Deep Ocean, Deep Sea Vents are the
only source of Chemical Energy and Food
Mobile Animals need to be able to locate
these Vents to eat - so they need eyes!!
EAT AT JOE’S
Once in a while you get
shown the light…..
In the strangest places…
If you look at it right.
Clock Reaction
 The first step in this reaction is the formation of triiodide
ion:
 H2O2 + 3 I- + 2 H+ --> I3- + 2 HO
 In the absence of thiosulfate ion the triiodide ion would
form the characteristic blue complex with starch.
However, the triiodide ion is rapidly reduced back to
iodide ion by thiosulfate:
 I3- + 2 S2O32- --> 3 I- + S4O62 In this clock reaction thiosulfate ion is the limiting
reactant. The blue starch-triiodide complex forms only
when all the thiosulfate ion has been consumed.
IO3- + 2 H2O2 + H+ = HOI + 2 O2 + 2 H2O (A)
HOI + CH2(CO2H)2 = ICH(CO2H)2 + H2O (B)