Dresden 2011 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
Q: Fachverband Quantenoptik und Photonik
Q 37: Cold Molecules III
Q 37.1: Vortrag
Mittwoch, 16. März 2011, 16:30–16:45, BAR Schön
Visible rovibrational spectroscopy of cold H3+ via chemical probing in a 22 pole trap — •Florian Grussie, Max Berg, Andreas Wolf, and Annemieke Petrignani — Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg
H3+ is the cornerstone of interstellar chemistry and the simplest triatomic molecule, therefore also of fundamental interest to experimental and theoretical physics. At the MPI for Nuclear Physics, spectroscopy on cold H3+ is performed in a cryogenic 22-pole radiofrequency trap using laser-induced reactions with argon as chemical probe. The chemical probing technique provides high sensitivity and a low background environment, so that transitions up to at least 6 orders of magnitude weaker than the fundamental (B21=4.77 · 1023 cm−3J−1s−1) can be observed. This high sensitivity is augmented by an efficient Daly detection system where each ion is amplified into a bunch of secondary electrons that are subsequently amplified into photons before being counted by a photomultiplier tube. This has allowed us to measure transitions from the two lowest rotational states of the H3+ vibrational ground state to, recently, final levels up to 16600 cm−1, i.e., half the dissociation energy. To observe transitions to even higher levels, the already low background needs to be minimized further. The background originates from non-laser-induced probe ions and laser photons. The latter should be eliminated by a new detection system insensitive to our laser photons. The non-laser-induced ions can be minimized by injecting the argon chemical probing gas during laser excitation only, using a pulsed valve.