Journal Article

FRAME: femtosecond videography for atomic and molecular dynamics

Li, Zheming, Bood, Joakim, Kristensson, Elias, Berrocal, Edouard, Aldén, Marcus, Ehn, Andreas

2017

Overview

Many important scientific questions in physics, chemistry and biology require effective methodologies to spectroscopically probe ultrafast intra- and inter-atomic/molecular dynamics. However, current methods that extend into the femtosecond regime are capable of only point measurements or single-snapshot visualizations and thus lack the capability to perform ultrafast spectroscopic videography of dynamic single events. Here we present a laser-probe-based method that enables two-dimensional videography at ultrafast timescales (femtosecond and shorter) of single, non-repetitive events. The method is based on superimposing a structural code onto the illumination to encrypt a single event, which is then deciphered in a post-processing step. This coding strategy enables laser probing with arbitrary wavelengths/bandwidths to collect signals with indiscriminate spectral information, thus allowing for ultrafast videography with full spectroscopic capability. To demonstrate the high temporal resolution of our method, we present videography of light propagation with record high 200 femtosecond temporal resolution. The method is widely applicable for studying a multitude of dynamical processes in physics, chemistry and biology over a wide range of time scales. Because the minimum frame separation (temporal resolution) is dictated by only the laser pulse duration, attosecond-laser technology may further increase video rates by several orders of magnitude. Ultrafast photonics: videography technique achieves femtosecond resolution A technique for capturing ultrafast moving images paves the way for a deeper understanding of some fundamental processes in nature. There are currently no methods for effectively videoing many dynamic processes that occur at molecular and atomic levels in physics, chemistry and biology. Marcus Aldén and colleagues from Lund University, Sweden, have demonstrated ultrafast videography capable of capturing images down to femtosecond time scales. Their technique, which they call Frequency Recognition Algorithm for Multiple Exposures (FRAME), involves superimposing a structural code onto the illuminating light to encrypt a single event, which is deciphered in post-processing. Its frame rate is limited only by the laser pulse duration. The team demonstrated a temporal resolution of 200 femtoseconds, but they believe it could be boosted by 1000 times by employing an attosecond laser.

• Publisher: Nature Publishing Group UK,Springer Nature B.V,Nature Publishing Group
• Subject: 140/125 / 639/624/1107/510 / 639/624/1107/527 / 639/766/400/584 / Applied and Technical Physics / Atomic / Classical and Continuum Physics / Lasers / Molecular / Optical and Plasma Physics / Optical Devices / Optics / Original / original-article / Photonics / Physics / Physics and Astronomy / Scientific imaging / Spectrum analysis / Video