Where Chemistry Can Take You From the lab to the Stars Switzerland
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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 Mathematician Teacher Doctor Lawyer 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
CuNO3 + NaC2O4 CuC2O4.xH2O 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
C
1
C m, 1
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. D t
6 6 3 10
0.9999
N C
tmax . Dt , k 2 tmax ,k 2
N( tmax . Dt , k ) C
Classical
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. D t
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 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)
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