Further Into the Atom with Ultrafast Light

Neomi Lewis ‘21

Figure 1. Protons carry magnitudes of different energies when compared to each other and this is evident in not only their speeds but also their impacts.

A great deal of modern atomic physics seeks to plumb the hidden depths of the atom, particularly the dynamics of inner-shell electrons about which not much is known. Attosecond, or 1×10-18 of a second, laser technology used by the Laboratory for Attosecond Physics, run by both LMU Munich and the Max Planck Institute of Quantum Optics, has recently been able to create bursts of high-energy photons with remarkable intensities high enough to allow for the observation of the interactions amongst multiple photons in a single pulse with electrons in the inner orbital shell of an atom.

Most of the research in the field of ultrafast high-energy optics uses a ‘pump-probe’ method to film the motion of the particles in question. A pump pulse first excites the electrons within the atom, which is shortly followed by a probe pulse. The probe is used to monitor the effect the pump photons had on the electrons. In order for both a pump and probe to act in succession, the photons in the beam must be tightly packed enough for the relevant electrons to be hit by them. In addition, if the photons aim to target inner electron shells, they must have sufficiently high energies. Until the recent success at the Laboratory for Attosecond Physics, these conditions have been difficult to achieve.

The team has been able to create these high densities by up scaling conventional sources of attosecond pulses. These innovative lasers contain 100 times as many photons per pulse as is used elsewhere.

Having two pulses probe inner atomic shells allows for better observation of electron dynamics with less interference. Even further, as Dr. Boris Bergues, the leader of the new study claims: the electron dynamics in the inner shells of atoms are of particular interest, because they result from a complex interplay between many electrons that interact with each other.

With this new attosecond source ready to use in experimentation, the secretive inner world of the atom and its complex dynamics begins to offer greater clarity and understanding.



  1. B. Bergues, et. al., Tabletop nonlinear optics in the 100-eV spectral region. Optica 5, (2018).
  2. Image retrieved from: https://www.flickr.com/photos/gsfc/4058451581

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