Hannover 2010 – scientific programme

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MO: Fachverband Molekülphysik

MO 6: Cold Molecules I

MO 6.7: Talk

Tuesday, March 9, 2010, 15:45–16:00, F 142

Vibrational Spectroscopy of H₃⁺ - advancing into the visible spectral region — •Max Berg, Dennis Bing, Annemieke Petrignani, and Andreas Wolf — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg

The triatomic hydrogen ion H₃⁺ is a highly reactive key component in many astrophysical and technological plasmas. Being the simplest polyatomic molecule, it is also an important benchmark system against which various quantum mechanical calculations are tested. While the rovibrational levels near the triangular equilibrium structure are well understood, the rovibrational spectrum of this elementary system at strongly deformed geometry, above the barrier to linearity near 10000 cm⁻¹, represents a formidable task for theory. Its experimental exploration so far ended slightly above 13900 cm⁻¹ from the ground state E₀ (λ ∼ 720 nm). We report new measurements in a cryogenic 22 pole trap in the range of very high vibrational overtones, reaching levels up to ∼16500 cm⁻¹ (λ∼600 nm) from E₀. Chemical probing spectroscopy revealed its use for ultra-sensitive detection of transitions six to seven orders of magnitude weaker than the fundamental. Aside from the transition frequencies (± 0.005 cm⁻¹), we present results from a new method to derive precise transition intensities, helping theoretical assignement of the lines.