electron tunneling from atoms
Just as a valley stabilizes the position of a body by gravity, the electric force attracting electrons to the atomic nucleus stabilizes them within a tiny volume of space, allowing the stable existence of atoms, the building blocks of our world. This stabilizing effect can also be represented by a valley, which physicists call a potential. According to the laws of quantum physics
, microscopic particles can penetrate the potential wall confining their location like a wave. If the wall is sufficiently thin, the wave may reach its other side, i.e. the particle may overcome the potential barrier without climbing it. This phenomenon has been dubbed tunnelling and constitutes one of the most striking implications of quantum physics. Tunneling of particles through some binding potential is commonplace in the microscopic world: it is believed to be responsible for nuclear as well as electronic phenomena, but – because of its awesome rapidity – it has never been observed in real time. This unsatisfactory state of matters has changed profoundly, when attosecond metrology permitted capturing electrons in the act of their tunnelling through the potential binding them to the atomic core under the influence of laser light. The experiment provides the first direct insight into the attosecond-scale history of electron tunnelling and reveal how light-field-induced tunnelling can be exploited for real-time observation of intra-atomic or intra-molecular motion of electrons.
, microscopic particles can penetrate the potential wall confining their location like a wave. If the wall is sufficiently thin, the wave may reach its other side, i.e. the particle may overcome the potential barrier without climbing it. This phenomenon has been dubbed tunnelling and constitutes one of the most striking implications of quantum physics. Tunneling of particles through some binding potential is commonplace in the microscopic world: it is believed to be responsible for nuclear as well as electronic phenomena, but – because of its awesome rapidity – it has never been observed in real time. This unsatisfactory state of matters has changed profoundly, when attosecond metrology permitted capturing electrons in the act of their tunnelling through the potential binding them to the atomic core under the influence of laser light. The experiment provides the first direct insight into the attosecond-scale history of electron tunnelling and reveal how light-field-induced tunnelling can be exploited for real-time observation of intra-atomic or intra-molecular motion of electrons.More information:
The first time-resolved observation of the quantum mechanical process of tunnelling has been reported by:
Attosecond real-time observation of electron tunnelling in atoms, M. Uiberacker et al., Nature 446, 627 (2007)
Attosecond laser pulses illuminate fleeting dance of electrons, Yudhijit Bhattacharjee, Science 316, 33 (2007)
Electrons caught tunnelling out of atoms Hazel Muir, Physics Today, 6, 27 (2007).
The experiment was listed among the ten physics highlights of the year 2007 by the American Institute of Physics.
Commented, among others, by:
Tunnel vision J. P. Marangos, Nature 446, 619 (2007)Attosecond laser pulses illuminate fleeting dance of electrons, Yudhijit Bhattacharjee, Science 316, 33 (2007)
Electrons caught tunnelling out of atoms Hazel Muir, Physics Today, 6, 27 (2007).
The experiment was listed among the ten physics highlights of the year 2007 by the American Institute of Physics.
Fig. 1. In the macroscopic world obeying to the laws of classical physics, a barrier must be climbed to overcome it. In the microcosm, the laws of quantum physics permit the particle to “tunnel” through a barrier. (© thn)