Ghost particles demonstrated in molecules
Researchers from the LaserLaB at the VU University Amsterdam and the FOM Foundation have demonstrated that the effects of ghost particles, which can be explained in the theory of quantum electrodynamics, not only play a role in atoms but also in molecules. They demonstrated this by carrying out precise laser measurements on the energy levels of specially prepared hydrogen molecules, which rotate very rapidly on their axes. The outcomes of these measurements was published on 22 July in the renowned journal Physical Review Letters.
QED
The energy levels of atoms and molecules can be calculated with considerable accuracy by solving the Schrödinger equation. This equation very accurately describes how two protons and two electrons move in a hydrogen molecule. Ghost particles, however, continually escape from the 'vacuum'. Although these cannot be measured directly, their existence can be demonstrated. The ghost particles in question are electron-positron pairs and virtual photons. All electrons are continuously surrounded by such ghost particles, which have a minimal effect on the energy states. The extremely small effects can be calculated using the theory of quantum electrodynamics (QED); the advanced calculations were recently performed by Professor Pachucki and his fellow researchers at the University of Warsaw. In their published article, the energies of a series of states with an increasing 'rotation number' were measured with considerable accuracy and compared with these calculations. This revealed that the effects of the ghost particles also exist in hydrogen molecules, and that these can be both calculated and measured. With this it has been demonstrated that they play a role in the chemical bonding of molecules.
Rapidly rotating hydrogen molecules
Hydrogen molecules with 'high rotational states' were prepared for the experiment by firing a UV laser at hydrogen bromide (HBr) molecules. The HBr molecules then disintegrated giving rise to an H atom that escaped with a high velocity. That H atom subsequently collided with a following HBr molecule, and in that chemical reaction a rapidly rotating hydrogen molecule was formed. The energy levels of these rotating molecules were then very accurately measured with a laser.
High precision testing of theories
This is the first time that this phenomena of ghost particles have been observed in molecules. With that it has been demonstrated that they influence chemical bonding in molecules. In the LaserLaB of VU University Amsterdam, the new FOM programme 'Broken mirrors and drifting constants - Ultra-precise investigations of fundamental symmetries and constants at the atomic scale' was recently started, which aims to test the boundaries of the QED theory and to explore if the effects of as yet unknown ghost particles can be observed.
Reference
The article QED effects in molecules; tests on rotational quantum states of H2 was published on 22 July in the journal Physical Review Letters. The authors of the article are Edcel Salumbides (Cebu, the Philippines, former FOM PhD), Gareth Dickenson (FOM PhD), Toncho Ivanov (VU) and Wim Ubachs (VU and FOM workgroup leader).
Further information
Prof. Wim Ubachs, LaserLaB VU
Website: http://www.nat.vu.nl/~wimu/
Telephone +31 20 598 79 48
Stichting FOM
Telephone +31 (0)30 600 12 22
Vrije Universiteit Amsterdam, Public Information Office
Telephone +31 (0) 20 598 56 66