Diffraction and Interference with Fullerenes:
Wave-particle duality of C60
The art of
hitting the goal with every shot
More recent experiments on fullerene interference:
"Wave-particle duality of C60"
Arndt , Olaf
Voss-Andreae, Claudia Keller,Gerbrand
van der Zouw,
Nature 401, 680-682, 14.October 1999
Contact us for
Introduction to de
Broglie Interferometry with large Molecules
Observation and application of matter waves has become one of the
leading themes in the development of experimental physics in the 20th
What we achieved
We have observed de Broglie wave interference of the
buckminsterfullerene C60 with a wavelength of about 3 pm
through diffraction at a SiNx absorption grating with 100 nm
period. This molecule is the by far most complex object revealing wave
far. The buckyball is the most stable fullerene with a mass of 720
atomic units, composed of 60 tightly bound carbon atoms.
Why should you
care about it ?
It is intriguing that C60 can almost be
considered to be a body obeying classical physics in view of its many
excited internal degrees of freedom. Leaving the source, it has as much
as 7 eV of internal energy stored in 174 vibrational modes, and highly
excited rotational states with quantum numbers greater than 100.
Fullerenes can emit and absorb blackbody radiation very much like a
solid and they can no longer be treated as a simple few level
Quantum interference experiments with large molecules, of the kind
first reported here, open up many novel possibilities among them
decoherence studies and nanolithography experiments.
A new kind of
football game :-)
While the mass of a buckyball does not agree with the
requirements for footballs (US: soccer balls) as defined by the
International Football Association (FIFA) the symmetry and shape of
this molecule actually does in all respects.
Note that the ratio between the diameter of a buckyball (1 nm) and the
width of our diffraction grating slits (50 nm) compares favorably with
the ratio between the diameter of a football (22 cm) and the width of a
goal (732 cm) according to FIFA standards.
The distance between the source and the detector corresponds in this
scaling to the distance between the Earth and the moon.
Setup of the
- C60 powder is heated to ~ 600 ... 700°C in a
resistively heated oven.
- The velocity distribution is very
broad and faster than purely thermal.
- The molecular de Broglie wavelength is centered at ~ 2.5
- The de Broglie wave length is thus ~ 400 times smaller than
the size of the particle
(1nm diameter of the electron shell)
- The hot and divergent beam is collimated to a pencil of ~
Buckyballs that pass the second slit are transversely cold
- The SiN diffraction grating has a
nominal gap width of 50nm and a grating constant of 100nm
- After free evolution over 1m the molecules are detected via
thermionic ionization by a tightly
focused Argon ion laser beam at 24 W.
- The positive ions are counted by a secondary electron
The velocity distribution
The most probable velocity of 210 m/s corresponds to a
deBroglie wavelength for C60 of ldB
= 2.5 pm !
The grating was manufactured by Tim
Savas, working in the group of Henry Smith at
A Look into the lab
Experimental Results: Diffraction of C60 at a SiN grating
Interpretation of the
- Interference fringes can clearly
- Theory and experiment in good
- molecules are highly excited, with
- molecules are fast and dispersed with
- different isotopes present in the
- Fitted gap width smaller than
design gap width
- contaminations ?
- van der Waals forces ?
- contrast currently mainly limited by
- width of velocity distribution
- variation of slit widths in the grating
Our Team (1999)
- C60 Nobel Prize
- H. Kroto, Sussex
R. Smalley, Rice
H. Kuzmany, Wien
-E. Campbell, Göteborg
E. Kolodney, Haifa
- Other groups active in fullerene research (1994)
Nanofabrication of SiN gratings:
Other groups currently working on
interferometry with nanogratings:
- D. E. Pritchard, MIT
- J. P. Toennies, MPI für Strömungsforschung
Quantum Optics and Atom Optics:
- Quantum Optics and Atom Optics Link Collection (D.
- Institute of Physics: Highlights of the year (quantum