Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 41: Interaction with VUV and X-ray light II

A 41.2: Talk

Thursday, March 20, 2014, 14:30–14:45, BEBEL E42

Time-resolved spectroscopy and coherent control of autoionizing states in neon — •Thomas Ding, Christian Ott, Andreas Kaldun, Alexander Blättermann, Kristina Meyer, Martin Laux, Veit Stooss, and Thomas Pfeifer — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany

The understanding of few- or many-electron dynamics represents a central topic of modern quantum mechanics. Information about the concerted motion of two or more bound electrons in atoms is encoded in the spectral resonance line shapes. In the experiment presented here we achieved coherent control of short-lived (femtosecond-domain) auto-ionizing wave-packet dynamics in neon (Z=10). Our transient absorption scheme involves a two-color two-photon pump step to coherently populate both spectroscopically bright (odd parity) and dark states (even parity) at the same time. This makes use of weak broadband atto-second-pulsed light in the extreme ultraviolet (XUV) energy range to excite the system into various doubly- and inner-valence-excited states lying ∼ 45 eV above the even-parity ground state. Moderately strong few-cycle near-infrared (NIR) pulses simultaneously facilitate the one-photon population transfer from those excited bright states to dark states. We study the initiated wave-packet oscillation under the influence of a time-delay-controlled and intensity-controlled replica of the NIR pump pulse inducing transient bright/dark level-couplings. This provides the opportunity to perform spectroscopy on dipole-forbidden states. Also, the method in principle allows to extract the coupling strength (dipole-matrix element) between quantum states.