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Benjamin McCall and Takeshi Oka University of Chicago Therese R. Huet Universite de Lille

Overtone and Combination Band Spectroscopy of H 3 +. Benjamin McCall and Takeshi Oka University of Chicago Therese R. Huet Universite de Lille James K. G. Watson National Research Council of Canada. About H 3 +. No electronic spectrum Equilateral triangle configuration

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Benjamin McCall and Takeshi Oka University of Chicago Therese R. Huet Universite de Lille

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  1. Overtone and Combination Band Spectroscopy of H3+ Benjamin McCall and Takeshi Oka University of Chicago Therese R. Huet Universite de Lille James K. G. Watson National Research Council of Canada

  2. About H3+ No electronic spectrum Equilateral triangle configuration  no allowed rotational spectrum n2x n1 n2y

  3. Importance of H3+ * Dominant ion in H2-dominated plasmas * n2 fundamental seen in emission on Jupiter * n2 seen in absorption in interstellar medium * As simplest polyatomic molecule, it is a benchmark for ab initio theory

  4. Why Study High Energy H3+? * 2n2 band discovered on Jupiter, higher bands may be observable * Emission from hot astronomical objects (planetary nebulae?) * Refinement of theoretical understanding * Breaking the barrier to linearity NGC 6543. Balick AJ 94, 671 (1987)

  5. H3+ Vibrational Bands 1/4800 1/840 1/270 1

  6. Experimental Technique Diode Laser Spectrum Analyzer Reference Cell Detector Discharge Cell Autobalancing Detector

  7. New Focus Diode Laser

  8. Plasma Conditions * p(H2) ~ 0.5 Torr * ~5 kV @ 6 kHz, 150 mA * liquid-N2 cooling

  9. New Focus “Nirvana” Detector “Autobalancing” detector outputs (S - g*R), where the gain ‘g’ is such that <(S - g*R)> = 0 at a user-selectable bandwidth

  10. Theoretical Predictions Watson Neale, Miller, & Tennyson

  11. Predictions for n1+2n20 n1+2n20 band is forbidden! Neale, Miller, & Tennyson Watson

  12. Lines Studied to Date Q(1,0) R(1,0) R(3,3) R(2,2) 3n23 P(3,3) R(1,1)-

  13. Representative Spectrum W N

  14. H2 Rydberg Transitions

  15. Summary of Detections Observed Assignment Watson Neale (cm-1) (J’G’U’)(JK) [O-W] [O-N] 7785.76 (1,3,2)(1,0) 7785.340 7786.009 [0.420] [-0.249] 7789.88 (4,6,2)(3,3) 7790.025 7790.156 [-0.145] [-0.276] 7822.38 (3,2,3)(2,2) 7822.250 7822.645 [3n23] [0.127] [-0.268] 7826.74 (2,0,2)(3,3) 7826.679 7827.115 [0.062] [-0.374] 7850.97 (2,4,2)(1,1) 7850.677 7851.250 [0.291] [-0.282] 7970.42 (2,3,2)(1,0) 7970.124 7970.698 [0.296] [-0.278]

  16. Future Work * Complete scan of n1+2n22 band (expect ~ 30 lines) * Comparison of observed lines and theoretical predictions * 4n2 band (Ti::Sapph laser) * 5n2 band? (Ti::Sapph)

  17. n1+2n22 Band Intensities

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