Where Chemistry Can Take You
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Transcript of Where Chemistry Can Take You
Where Chemistry Can Take You
From the lab to the Stars
From Utah to China, Japan & Switzerland
by Terry A. Ring, Ph. D.
Davis High Chemistry
Earning a Living with ChemistryTalk about some of my research
Making Powders by Crystallization[= Precipitation]
NucleationCrystal Growth
Making Nano ParticlesNano Particles = Big Surprises
Demonstration Clock Reaction
Ring’s Chemistry Competition
Go to College and Get an 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 GrowthChemistry Job Growth rate is
~14%/10 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/yrStarting 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 msSelf Assembly - 10 ms
Hexagonal Packing of Spheres
Light Diffraction
Defects in Ordered Arrays Bend Light
Optical Semiconductors
Photonic Crystal Light Pipe
Light PipeLight Leaving Pipe
Nano-sized Cluster Nucleation
IntroductionClassical Nucleation Theory & LimitationsNew Theory & Findings
Terry A. RingChemical EngineeringUniversity of Utah
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)
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
Silicon Particles
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).
0 10 20
18.3358
-0
( )GSis
....4 a12
.kB T
ig
2
3 1
ig
.0 ig
201 ,is ig
G(i) = - i kBT lnS + a ao2i2/3
Population Balances
Classical Nucleation = Single Atom Addition
ij=(i+j), Population Balance - Multi-atom Addition
ij=(i+j)exp(-Gij/kBT),
ii
kikiki
k
iikik CCCCtC
1,
1
1,2/1/
1,1111,12
1/ CCCCtC kkkkk
Quantum Mech. Classical
0 1 106
2 1063 10
60
0.5
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C,m 1
N( ),.m t 1
C,m 2
N( ),.m t 2
.m t0 0.05 0.1
0
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C,m 1
N( ),.m t 1
C,m 2
N( ),.m t 2
.m t
0 1 2 3 4 5 6 7 8 910
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N ,.tmax
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C,
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9k0 1 2 3 4 5 6 7 8 910
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1 1013
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1 108
1 107
1 106
1 105
1 104
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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 SizeQualitative similar to Si Plasma Expts
Collision Energetics
0 2 40
0.2
0.4
0.6
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Collision Trajectory, R/re
BE
/ n
(eV
)
BE (i+j)
o
BE j
o BE i
o
+
BE j
BE i
+* *
²E
EACrystallo- luminescence
Figure 3 Collision trajectory for collision between i=3 and j=4 clusters,showing ground state energies before and after collision, as well as theactiviation energy of collsion.
Crystalloluminesent Spectrum
Intensity vs Energy Intensity =
collisions/per unit time = photons/unit time
Wavelength E = hc/l
Human eye detection @ 3x104photons/cm2/s at λ 510 nm
0 0.5 1 1.5 2 2.51 10
141 10
131 10
121 10
111 10
101 10
91 10
81 10
71 10
61 10
51 10
40.001
0.01
0.1
I,i k
E,i k
eV
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 of) conditions...where the phenomenon is stronger,”
Barsanti, M. & Maccarrone,,F., 1991
3 References from 1991-2000 (2 India, 1 Russian)
Experimental Observations
Delay time is a function of concentration & mixing
Flashes are Short < 80 ns
Peak Count rates ~5-8x105 photons/s
Temporal & Spatial Bunching of Flashes
340nm<λ<380 nmBlue White Light
Gibbon, M.A., Sopp, H. , Swanson, J., and Walton, A.J., J. Phys. C. 21,1921(1988).
Saturated NaCl + Conc. HCl - 120 s observation time
Spectrum of Light NaCl Crystallization
Data fromdr KRZYSZTOF KLEDZIK
University of Gdansk
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 SpectrumWhere 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
Nanocluster, Ti14C13 with emission peak at 20.1 microns is seen in Egg Nebula byA.G.G.M. Thielens and M.A. DuncanScience 288,313(2000)
this joins some 120 other small molecules identified in the vicinity of stars, interstellar gas and dust clouds
Experimental Verification
Super Novae
Deep Sea Vents
C&E News 12/21/98National Geographic October 2000
Deep Sea Life
Salt Lake Tribune, 2/13/97National 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 but only 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- + S4O6
2- 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)