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The The nobelnobel prize in physics 1901prize in physics 1901

Wilhelm Conrad RöntgenGermany

“in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him"

Discovery of XDiscovery of X--RaysRays

1895, W.C. Röntgen:

Unknown “X”-Rays:high penetration

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“in recognition of the extraordinaryservices he has rendered by his discovery of spontaneous radioactivity"

"in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel"

Henri BecquerelFrance

Pierre CurieFrance

Marie CurieFrance

The The nobelnobel prize in physics 1903:prize in physics 1903:Discovery of radioactivity (1896)Discovery of radioactivity (1896)

Discovery of radioactivityDiscovery of radioactivityRutherford, 1900-1911- 3different types of atomic radiation- artificial transmutation of one element into another- Atoms contain small nucleus

Atoms are not elementary particles. They have complicated structure

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The The nobelnobel prize in chemistry 1908prize in chemistry 1908

“for his investigations into the disintegration of theelements, and the chemistry of radioactive substances"

Ernest Rutherford, UK

"in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases"

The The nobelnobel prize in physics 1906prize in physics 1906

Joseph John ThomsonUnited Kingdom

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Discovery of electronDiscovery of electron

1897, JJ. Thomson: Rays of discharge:– Have negative charge,– Consist of discrete particles–Determined the ratio e/m – me~0.001 m hydrogen

Electrons

Discovery of electronDiscovery of electron

1912, R.A.Millikan:

Charge of electrone = 1.6x10-19 C

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Structure of atomsStructure of atoms

Thomsons: “pudding” model

Structure of atomsStructure of atoms

Rutherford's Experiment - Planetar model

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Structure of atomsStructure of atoms

Atoms emit sharp spectral linesWhy?

Structure of atomsStructure of atoms

Bohr: Bohr: -- electrons are orbiting the nucleus-only orbits of certain radii (energies) are "permitted”, where electron :

has a defined energy state will not radiate energy will not spiral into the nucleus

E=Rh/n2

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The The nobelnobel prize in physics 1922prize in physics 1922

“for his services in the investigation of the structure of atoms and of the radiation emanating from them"

Niels Henrik David BohrDenmark

LIGHT LIGHT -- WAVE OR PARTICLE:WAVE OR PARTICLE:Black Body RadiationBlack Body Radiation

Black body: an idealized object which absorbs and emits all frequencies

Rayleign-Jean law Ultraviolet catastrophe

Planck, 1905:Planck, 1905:The energy of vibrating molecules can only have certain discrete values:

E=n*E=n*hfhf, n=0, 1, 2,...

h = 6.6 x 10-34 Js Planck’s constantBirth of quantum physics!Birth of quantum physics!

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LIGHT LIGHT -- WAVE OR PARTICLE:WAVE OR PARTICLE:Photovoltaic effectPhotovoltaic effect

An appearance of current in a vacuum tube under illumination

Hertz, 1887Hertz, 1887::- maximum electron energy is independent of the light intensity- existence of cutoff frequency

LenardLenard, 1902, 1902- maximum electron energy is determined by the light frequency

Einstein, 1905:Einstein, 1905:

light= quanta or photonslight= quanta or photonsE=E=hfhf

LIGHT LIGHT -- WAVE OR PARTICLE:WAVE OR PARTICLE:

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MillikanMillikan, 1916, 1916

Attempts (10 years of work!!!) to disprove Einstein's theory

Most convincing evidence for Einstein's theory

LIGHT LIGHT -- WAVE OR PARTICLE:WAVE OR PARTICLE:Photovoltaic effectPhotovoltaic effect

LIGHT LIGHT -- WAVE WAVE ANDAND PARTICLE: PARTICLE: E=E=hfhf

The The nobelnobel prize in physics prize in physics

“in recognition of the services he rendered to the advancement of Physics by his discovery of energy quanta"

Max Karl Ernst Ludwig PlanckGermany

19181918 19211921

Albert EinsteinGermany and Switzerland

“for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect"

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The The nobelnobel prize in physics 1923prize in physics 1923

“for his work on the elementary charge ofelectricity and on the photoelectric effect"

Robert Andrews MillikanUSA

Matter: Particle or WaveMatter: Particle or Wave

De Broglie, 1923:

Atomic orbits should be quantized becauseeach particle is also a wave:λ=h/mv

λel = 7*10-10 m, i.e. several times size of atom

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Matter: Particle or WaveMatter: Particle or Wave

C. J. Davisson, 1927: Electron diffraction from nickel crystal

G.P.Thomsom, 1927: Electron diffraction bythin foil

Electron is a wave

The The nobelnobel prize in physicsprize in physics

"for his discovery of the wave nature of electrons"

Prince Louis-Victor PierreRaymond de Broglie, France

"for their experimental discovery of the diffraction of electrons by crystals"

19371937

Clinton J.DavissonUSA

George P.ThomsonUK

19291929

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“for the creation of quantum mechanics, the application of which has, inter alia, led to the discovery of the allotropic forms of hydrogen"

The The nobelnobel prize in physicsprize in physics

19321932

Werner Karl Heisenberg Germany

“for the discovery of new productive forms of atomic theory"

19331933

Paul Adrien Maurice Dirac, UK

Erwin SchrödingerAustria

Heisenberg -

Matrix mechanicsUncertainty principle

New Quantum MechanicsNew Quantum Mechanics

Δx Δp > h/2ΔE Δt >h/2

A. Einstein:“God does not play dice”R. Feynman:“No one understands quantum mechanics”

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Schrödinger - Wave mechanicsH Ψ= EΨΨ - wavefunction∫ Ψ Ψ*dx = 1

New Quantum MechanicsNew Quantum Mechanics

New Quantum Mechanics: New Quantum Mechanics: TunnelingTunneling

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New Quantum Mechanics: New Quantum Mechanics: TunnelingTunneling

After the barrier:Ψ≠0 Tunneling

Transmission probabilityT ≈ e–2kL

k = [8π2m(U0 – E)]½/h

New Quantum MechanicsNew Quantum Mechanics

Dirac - Prediction of spin- Prediction of antiparticles(positron)

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"for the discovery of the Exclusion Principle, also called the Pauli Principle"

The The nobelnobel prize in physics 1945prize in physics 1945

Wolfgang PauliAustria

Ernst RuskaGermany

Gerd BinningGermany

Heinrich RocherGermany

The The nobelnobel prize in physics 1986prize in physics 1986

"for his fundamental work in electron optics, and for the design of the first electron microscope"

"for their design of the scanning tunneling microscope"

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Electron: Particle and Electron: Particle and WaveWave

Light microscope:

Size of an object is limited by the wavelength of light.

Transmission Electron microscopes

Use electrons as a "light source" much lower wavelength a resolution of a thousand times better than with a light microscope.

Seeing with electrons: Transmission Electron MicroscopeSeeing with electrons: Transmission Electron Microscope

Seeing with electrons: Scanning Electron MicroscopeSeeing with electrons: Scanning Electron Microscope

Scanning electron microscopy (SEM): scanning a focused probe across the surface of the sample.

Detection: Secondary electrons emitted from the sample detected by a photomultiplier system. The output - modulate the brightness of a TV monitor that is rastered in synchronisation with the the electron beam scan. The more electrons a particular region emits, the brighter the image at that point.

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Seeing with electrons: Scanning Electron MicroscopeSeeing with electrons: Scanning Electron Microscope

Black Widow spider claw An ant holding a microchip

Electrons tunnel between the surface and the stylus

an electrical signal.

Size of the stylus tip - single atom. It slowly scans across the surface. The stylus is raised and lowered in order to keep the signal constant and maintain the distance.

Smallest details of the surface !

Seeing with electrons: Scanning Tunneling MicroscopeSeeing with electrons: Scanning Tunneling Microscope

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Individual atoms (10-10 m) can clearly be seen !!!

Seeing with electrons: Scanning Tunneling MicroscopeSeeing with electrons: Scanning Tunneling Microscope

Platinum Silicon