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Visible transitions from ground-state H 3 + and their Einstein-B coefficients measured with high-sensitivity action spectroscopy Dr. Annemieke Petrignani MPI for Nuclear Physics, Heidelberg (Current affiliation: Leiden Observatory) Royal Society Discussion Meeting Chemistry, astronomy and physics of H 3 + 9-10 February 2012

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Outline Introduction Action spectroscopy on Cold H 3 + in a 22-pole ion trap Visible Transitions of H 3 + –Transition Frequencies –Einstein B coefficients Conclusions & Discussion 2

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Introduction Theory 3 Munro et al., Mol. Phys. 104 (2006) 115 Einstein A Coefficients Band Origins (cm -1 ) r R almost no exp data exp well studied Horseshoe States

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Introduction Theory & Experiment … previously Theory SAH (Schiffels, Alijah, Hinze) 2003 corrected using [1] T. Oka and co., Absorption Spectroscopy Population distributed over many J (overtones and hot bands) High H 3 Rydberg background Laboratory Oka & co: [1] Gottfried et al. 2003 [2] Gottfried et al. 2006 [3] Morong et al. 2009 Sensitivity limit reached Gottfried et al. 2006 4

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55 K Laser H3+H3+ He Ar H2H2 H2H2 H 3 + (v≥2) + Ar ArH + + H 2 H 3 + (v<2) + ArArH + + H 2 buffer gas reactant gas Action Spectroscopy on Cold H 3 + in a 22-pole ion trap 5 E p (eV)ΔE p (eV) H2H2 4.38/ O2O2 0.014 Ar3.840.55 N3.560.83 F3.540.86 F2F2 3.450.94 Ne2.072.32 He1.852.54

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Action Spectroscopy on Cold H 3 + in a 22-pole ion trap 55 K Laser H3+H3+ H3+H3+ H3+H3+ He Ar ArH + H3+H3+ H2H2 ++ Ar H3+H3+ H3+H3+ H3+H3+ ArH + H2H2 H2H2 buffer gas reactant gas BG non laser-induced ArH + Signal laser-induced ArH + 6

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Action Spectroscopy on Cold H 3 + in a 22-pole ion trap 55 K Laser H3+H3+ ArH + H2H2 H2H2 BG non laser-induced ArH + Signal laser-induced ArH + 7 background sources - photons (minimal) - ambient - laser (λ dependent) - ArH + - initial H 3 + - ArH + lifetime differential pumping high P[H 2 ] low P[H 2 ] scintillator + Al PMT + filter

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Action Spectroscopy on Cold H 3 + in a 22-pole ion trap unknown J=1-2 predictions of Schiffels, Alijah, Hinze, 2003 Neale, Miller, Tennyson, 1996 aid search, choose observable transitions & give assignments predictions of Schiffels, Alijah, Hinze, 2003 Neale, Miller, Tennyson, 1996 aid search, choose observable transitions & give assignments Theory – Exp – 10 14 10 13 10 19 T1T2T3 1.6 8 A. Petrignani et al. 2009 search window up to 10 cm -1 !!! M.H. Berg, PhD Thesis, 2011 NMT96 SAH03 SAH03c (AA10) (JT pc)

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Transition Frequencies Previously… <13,700 cm -1 TiSa laser 10 3 H 3 + ions 10 -4/5 x fundamental B 00 01 0.01 cm -1 absolute resolution 0.001 cm -1 relative resolution 23 Transitions frequencies 17 new, 6 known In agreement with Gottfried 2003 [4] Kreckel et al., JCP 129 (2008) 164312 [5] M. Pavanello et al., Phys. Rev. Lett. 108 (2012) 023002 9

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Transition Frequencies >15,000 cm -1 TiSa & Dye laser (DCM & Rh. B) 10 4 -10 5 H 3 + ions 10 -6 x fundamental B 00 01 0.005 cm -1 absolute resolution <0.001 cm -1 relative resolution 3 weak transitions <13,700 cm -1 7 transitions >15,000 cm -1 [4] Kreckel et al., JCP 129 (2008) 164312 [5] M. Pavanello et al., Phys. Rev. Lett. 108 (2012) 023002 10

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Transition Frequencies Theory & Experiment… updated Theory NMT: Neale, Miller, Tennyson, 1996 SAH: Schiffels, Alijah, Hinze 2003 unscaled 2003 scaled using [1] Alijah J. Mol. Spectrosc. 264 (2010) 111 using [1-5] 11 Laboratory Oka & co: [1] Gottfried et al. 2003 <13,700 cm -1 [2] Gottfried et al. 2006 [3] Morong et al. 2009 MPI: [4] Kreckel et al. 2008 <17,000 cm -1 [5] M. Pavanello et al. 2012 total 35 transition frequencies from J=1

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Transition Frequencies Theory & Experiment… latest status! 12 BO+DA BO+DA+REL BO Born-Oppenheimer approximation DA Diagonal Adiabatic correction REL Relativistic effect M. Pavanello et al. Phys. Rev. Lett. 108 (2012) 023002 average deviation of 0.1 cm -1 !

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N ArH+ B 12 · N H3+ ·P L · A ·[1-exp(-t LIT / A )] · T 10 5 Relative Normalisation Constant conditions Dynamic count range J=1-2 10 -1 /10 0 Einstein B Coefficients measuring line intensities Absolute Normalisation Reference line (0,0 0 ) (0,3 1 ) “Known” Einstein B coefficient Measured for every transition 13 VIS: ~10 -6 x fundamental

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Einstein B Coefficients Theory & Experiment 14 Munro et al., Mol. Phys. 104 (2006) 115

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Einstein B Coefficients Theory & Experiment 15

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Conclusions & Discussion Observation of ro-vibrational levels –up to 17,200 cm -1 (dissociation ~35,000 cm -1 ) –35 frequencies, 18 probabilities Good agreement with theory Resolution –Relative <0.001 cm -1 –Absolute ~0.005 cm -1 (calibration to Li lines) 16

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Conclusions & Discussion Extend spectroscopy to above 17,000 cm -1 –Use Neon or Helium as probe gasses lower background, lower T –Improve sensitivity lower photon background (timing) lower non-laser induced ArH + (pulsed valve) increase H 3 + –Use improved predictions <0.3 cm -1 (10 cm -1 deviation gives ~10 day search) –Prediction-independent search 17 Sensitivity increased by 10 2 Transitions intensities down to B ij ~10 17 cm 3 /Js 2 Sensitivity limit not reached yet

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Acknowledgements Max Berg Dennis Bing Florian Grussie Holger Kreckel Andreas Wolf Sascha Reinhardt – currently at MPI für Quantenoptik, Germany AP – currently at Leiden Observatory, NL Many thanks to Jonathan Tennyson and co-workers, UCL, UK Alexander Alijah, Reims University, France 18

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19 Thank you for your attention

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