Where Chemistry Can Take You From the lab to the Stars Switzerland

June 20, 2018 | Author: Anonymous | Category: Science, Astronomy, Particle Physics
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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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