gold for plasmotics by tom heinrich. why is gold so special ?

Gold for Plasmotics

By Tom Heinrich

Why is gold so special ?

More facts about gold metal bonding

Cubic-face-centered (111)

lattice constant a~0,4 nm

electron-dense n~5,98 E 28 m^(-3)

[Xe] 4f->14 5d->10 6s->1

mean free path lamda = 42nm

www.ww.tu-freiberg.de/mk/Dokumente/.../Vorlesung15.ppt

Which elements do you use normaly for Nanopartikels ?

The biggest manufacter produces nanoparticels out of nobel / royal metals.

- Gold Nanoparticles

- Silver Nanoparticles

- Copper nanoparticles

- Platinum and Palladium nanoparticles.

What makes a metal nobel ?

.... are metals that are particularly resistant to corrosion.

Better solution for us :

nobel metal = copper, silver, gold,

completely filled d-bands

no contribute to the conductivity and reactivity

Let us have a closer look at

copper, silver and gold.

The 3 metals withe the most distinctive shining .

How could it be that silver and gold have neary the same atomic radius ?

Remember gold have 32 more protons than silver !

http://www.businessinsider.com/biography-of-albert-einstein-2013-1

Sire pleace, the answer is :

Relativistic quantum effect in chemistry

What is the Relativistic quantum effect ?

Properties of heavy atoms

s-orbital electros have nearly speed of light

mass growth --> contraction of the s orbitals

s-electrons shild the nuclear charge

the energy levels of the other orbitals is lifted up

What does this mean for us ?

Valence and conductor band approaching

easier to stimulate elektros from d to s aka "Interbandanregung"

for gold start at 520 nm (~ 2,38 eV)

nearly free electrons in 6sp orbital

Band-stucture of Gold

Dielectric function

Model of Drude-Sommerfeld

electrons = findependent, point-like and effectively-free

accelerate by external electric field

decelerate Collisions with metal ions

Г = T^( -1) with T = time between two hits --> Variancefactor --> only effectively-free electrons

http://upload.wikimedia.org/wikipedia/commons/4/4d/Electrona_in_crystallo_fluentia.svg

OK, but now seriosly why do the most of physicy use gold for thier experiments and not silver or copper ?

Ask yourself with which spoon do you eat your "sunday-morning-egg" copper, silver or gold ?

Problem : We were talking about Bluks !

http://www.vanillabanking.de/wp-content/uploads/2012/10/goldbarren-gold-bar.jpg

Solution : let´s shrink to nanopartikel

Über neue Synthesewege für ultrakleine, fluoreszente „Gold-Nanopartikel“ und deren Einbau in Materialien by Andre Schäfer

Effects of shrinking to nanoscale

Bigger surface by a minimum of volumina

-> surface-energy lifted up

-> other wavelength of the surface plasmos

-> other absorbation of light

discrete energy levels

excited electron gas

-> aktive chemical Gold nanostructures: engineering their plasmonic properties for biomedical applications

Influence of the surface

http://www.sigmaaldrich.com/content/dam/sigma-aldrich/materials-science/nanomaterials/gold-nanostructures/figure-1.jpg

Where is the use ?

Yesterday Coulering "Glas"

Today Medicin, marking,

Tomorrow Next generation of super-computers

Contrast enhancement for optical imaging

Spatially resolved spectra biological sample(Phantom)

Hauptquelle

Gold nanostructures: engineering their plasmonic properties for biomedical applications

Contrast enhancement for optical imaging

Gold nanostructures: engineering their plasmonic properties for biomedical applications

All good things come to an end ...

And so

Fin

My feelings about all of this.