Researcher Intends to Extend the Application of Attosecond Spectroscopy into Soft X-Ray Region

This year, at the Max Planck Institute of Quantum Optics (MPQ), attosecond research has received a further thrust. Matthias Kling (LMU Munich) has been appointed by the Max Planck Society as a Max Planck Fellow at the MPQ for five years.

From January 2019, Kling will lead a new research team in Ultrafast X-Ray Imaging and Spectroscopy in the Laboratory for Attosecond Physics (LAP), joining hands with the division of Ferenc Krausz.

The Max Planck Society launched the Max Planck Fellow program in 2005, the goal of which was to strengthen the collaboration between its institutes and local universities. The program allows awardees to establish their own research teams in the receiving institutes. Matthias Kling, being a Max Planck Fellow, intends to extend the use of attosecond spectroscopy at MPQ further into the soft X-ray region.

Attosecond spectroscopy renders it feasible to analyze ultrafast processes, for example, electronic motion, in real time—that is, on scales of a few hundred attoseconds or less (1 attosecond = 10⁻¹⁸ seconds). The specialized laser infrastructure available at the Laboratory for Attosecond Physics offers a perfect basis for Kling’s new venture, since it has the potential to generate the ultrashort laser pulses required to investigate the dynamics on this scale at very high repetition rates.

An innovative 100-kHz laser in LAP will be used as the primary light source for generating the attosecond pulses. This device has the ability to produce 100,000 laser pulses per second, where each pulse lasts for a few femtoseconds (1 fs = 10⁻¹⁵ seconds). Kling and his team intend to use this laser to generate femtosecond pulses in the mid-infrared range, and use the pulses to produce attosecond pulses that have wavelengths in the soft X-ray region, more particularly in the frequency interval called the water window.

The water window incorporates the section of the electromagnetic spectrum corresponding to wavelengths from 2.3 to 4.4 nm. Radiation that has wavelengths in this range has the ability to penetrate water to depths of about 1–10 μm and is primarily absorbed by the carbon, nitrogen, and oxygen atoms that occur in organic molecules. This denotes that it is possible to use attosecond pulses of laser light in this wavelength range to investigate the metabolic transformations and behavior of organic compounds in their natural aqueous environment. In the long run, the technology could offer innovative understanding about the origins of radiation-induced molecular transformations and enable the timely diagnosis of life-threatening diseases like cancers.