Download Brief presentation of the history of atomic physics

(Rough) Historical survey of
Atomic Physics
Atoms in the classical antiquity
Leucippus and Democritus (fifth to fourth
century B.C.) postulated that all matter is built
up from indivisible units – the atoms.
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The beginnings of atomic physics
Antoine-Laurent de Lavoisier, 1743 (Paris) – 1794 (Paris)
Law of conservation of mass: the mass of closed system
remains constant, regardless of the processes inside
the system
Joseph Louis Proust, 1754 (Angers) –1826 (Angers)
Law of definite proportions: The elements in a chemical
compound always occur in the same proportion by mass
(NaCl: always 40% Na and 60% Cl)
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The beginnings of atomic physics
John Dalton,
1766 (Eaglesfield, Cumberland) – 1844 (Manchester)
Law of multiple proportions: Elements combine to chemical
compounds in a ratio of small whole numbers (CO, CO2)
Dalton’s law of partial pressures
List of atomic weights
Dalton’s Atomic theory: Elements are made up from indivisible
and undestroyable atoms, which are characteristic for the element. Atoms of
different elements can combine to chemical compounds, and for a given
chemical compound they always combine in the same ratio.
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Solar spectra
Joseph von Fraunhofer,
1787 (Straubing) –1826 (Munich)
Measurement and detailed mapping of absorption lines in solar spectrum
(the so-called Fraunhofer lines)
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The emission spectrum of atomic hydrogen
Anders Jonas Ångström,
1814 (Lögdö bruk, Medelpad) – 1874 (Uppsala)
Solar spectrum: showed by means of optical spectroscopy
that the sun contains hydrogen
Johann Jakob Balmer, 1825 (Lausen, CH) – 1898 (Basel)
Balmer formula: empirical formula for the energies of
six of the spectral lines observed in the emission spectrum
of hydrogen (1885)
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The emission spectrum of atomic hydrogen
Janne (Johannes Robert) Rydberg,
1854 (Halmstad) – 1919 (Lund)
Rydberg formula: generalised Balmer’s formula
to the other series of the hydrogen emission spectrum
Theodore Lyman,
1874 (Boston) – 1954 (Cambridge, MA)
Hydrogen emission series in the ultraviolet
Friedrich Paschen,
1865 (Schwerin) – 1947 (Potsdam)
Hydrogen emission series in the infrared
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The discovery of subatomic particles
Sir Joseph John Thomson,
1856 (Cheetham Hill) – 1940 (Cambridge)
Discovery of electron (”corpuscle”) in a series of vacuum
tube experiments in 1897.
Atomic model: corpuscles in a sea of positive background
(”plum pudding model”)
Lord Ernest Rutherford,
1871 (Brightwater, New Zealand) – 1937 (Cambridge)
Postulated the existence of the atomic nucleus on the basis
of the gold foil experiment
Rutherford model of the atom: nucleus, containing the main
part of the atomic mass, surrounded by the light electrons
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The introduction of the energy quantum
Max Planck, 1858 (Kiel) – 1947 (Göttingen)
Planck’s law: Introduced in 1899/1900 the energy
quantum E = hν in order to be able to derive a
formula for the spectral distribution of black-body
Radiation.
Albert Einstein, 1879 (Ulm) – 1955 (Princeton)
Photoelectric effect: mathematical description 1905
Theory of (stimulated and spontaneous) emission and
absorption (1916)
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The Bohr model
Niels Bohr, 1885 (Copenhagen) – 1962 (Copenhagen)
Bohr model of the atom (1913): Electrons in orbits around
the nucleus. Only certain orbits with a fixed energy are allowed,
and the electron looses energy only if it jumps between the
orbits. The lost energy is emitted as light.
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The particle-wave duality
Louis de Broglie, 1892 (Dieppe) – 1987 (Louveciennes)
Particle-wave duality: Postulated in 1924 that all moving
objects or particles have an associated wave:
λ = h/p
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The spin
Wolfgang Pauli, 1900 (Wien) – 1958 (Zürich)
Spin: Introduced in 1924 a new quantum number,
which later was identified with the z-component of the
spin.
Exclusion principle (1925): no two electrons can exist in the same
quantum state (later extended to all Fermions)
Spectrum of the hydrogen atom: used in 1926 the
Heisenberg-Born formulation of quantum mechanics to
derive the spectrumof atomic hydrogen
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The Schrödinger equation
Erwin Schrödinger, 1887 (Vienna) – 1961 (Vienna)
Schrödinger equation (1926): Describes the motion of
an electron in terms of a wave function:
i
∂
Ψ (r , t ) = H Ψ (r , t )
∂t
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The matrix formulation of quantum
mechanics
Werner Heisenberg, 1901 (Würzburg) – 1976 (Munich)
Max Born, 1882 (Breslau) – 1970 (Göttingen)
Pascual Jordan, 1902 (Hannover) –1980 (Hamburg)
Provided in 1925 a formulation of quantum mechanics, in which the operators
are time-dependent rather than the wave functions. This formulation is an
alternative to the Schrödinger formulation.
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The first relativistic formulation of quantum
mechanics
Paul Dirac, 1902 (Bristol) – 1982 (Tallahassee)
Dirac equation (1928): formulated the first relativistic theory of
quantum mechanics. In the non-relativistic limit the
Dirac equation leads to the Schrödinger equation with
relativistic contributions.
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Atomic Physics
today
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Atomic Physics and the Sciences
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Atomic Physics and the Sciences
Three examples from
Modern Atomic Physic
Condensed Matter Physics
Astrophysics
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Pump-probe spectroscopy
(a)
(c)
(b)
(d)
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Measuring the lifetime of an excited state
Excited states of Xe atoms decay
primarily by the Auger decay
Uiberacker et al., Nature 446 (2007) 627
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Atomic physics → Molecular physics
→ Condensed matter physics
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Can atoms be made visible?
TR Linderoth et al.
Phys. Rev. Lett. 82 (1999) 1494
Aarhus Universitet
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|Wave functions|2 made visible
Iron atoms arranged on a
Cu surface
C60 molecules on a Si(111)
surface: Experiment and theory
E. Canadell et al.,
J. Mat. Chem. 11 (2001) 1
IBM Almaden
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Quick reminder
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Single atoms on surfaces
From lecture by Angelos Michaelides,
Fritz-Haber-Institut Berlin, University College of London
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Atomic Physics in Astrophysics
”Atomic physics plays a key role in astrophysics
as astronomers' only information about a
particular object comes through the light that
it emits, and this light arises through atomic
transitions.”
- Homepage Atomic Astrophysics Group,
University of Cambridge
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Atomic Physics in Astrophysics
Solar and Heliospheric Observatory
(SOHO)
Common project by ESA and NASA to
study the Sun
• Launched in 1995
• Works at 1.5 million kilometers from the Earth
• Contains 12 different instruments including
different particle analysers and spectrographs
http://sohowww.nascom.nasa.gov/
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SUMER instrument on board of SOHO
SUMER = Solar ultraviolet measurements of emitted radiation
http://www.mps.mpg.de/projects/soho/sumer/
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UV emission spectrum of the Sun,
30th January 1996
SUMER instrument on board of SOHO
Observation
Data analysis:
Line identification by comparison
to literature values
Comparison from literature values
Provides information on
elemental composition,
Temperature, etc., of different
parts of the sun.
http://www.mps.mpg.de/projects/soho/sumer/
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