Berlin 2014 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 13: Posters 3: Cold Molecules, Helium Nano Droplets, and Experimental Techniques

MO 13.37: Poster

Mittwoch, 19. März 2014, 16:30–18:30, Spree-Palais

Fine structure and fragmentation of n=4 states in H3 — •Steffen J. Meyer, Peer C. Fechner, and Hanspeter Helm — Albert-Ludwigs-Universität, Freiburg, Germany

Neutral triatomic hydrogen is the most simple polyatomic molecule, and a prototype of molecular degrees of freedom, of molecular interaction and of nonadiabatic couplings in particular.

In this contribution we present our results on the three-body fragmentation of principal quantum number n=4 states in H3, which are coaxially or perpendicularly excited using a narrowband tunable diode laser in a keV neutral beam.

Precise continious frequency tuning allows us to measure and compare the fine structure splitting of the vibrational ground state and vibrational excited states. The splitting depends on the coupling of electronic spin with the various angular momenta of the molecule.

The excited states decay primarily by predissociation into the continuum of three neutral H atoms. Time- and position-sensitive detectors allow to record in coincidence the three slow (≈ 1 eV) neutral ground state hydrogen atoms which emerge in predissociation.

Coincident detection of the three correlated atoms from a single molecule permits to reconstruct the centre-of-mass momentum vectors of the three hydrogen atoms. This experiment, when repeated for many molecules (≈ 104) delivers a map of momentum correlation of the three H atoms. The observed distribution is a measure of the phase-space dependent action of nonadiabatic coupling which allows the bound state to exit into the continuum.

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