Physics, Chemistry and Astronomy of H 3 + Royal Society Discussion Meeting And the Satellite Meeting January 16-18, 2006

Theoretical Spectroscopy Rigorous calculation Triplet excited state Asymptotic vibrational states Sub-microhartree PES Hyperspherical coordinate 1975 H 2

Laboratory spectroscopy Near-infrared to visible, above the barrier Action spectroscopy H 2 D +, HD 2 +, D 3 + Ultra-cold H 2 +, H 3 + and isotopomers mK Spectroscopy using quantum logic 25 vibrational bands cm -1

Dissociative recombination Rotationally cooled H 3 + CRYRING, TSR Theoretical calculation Full dimentional calculation Jahn-Teller effect

Chemical kinetics 22-pole ion trap H + + H 2 and H H 2 and deuterium variants

Surprise in diffuse cloud Same column density in dense and diffuse clouds N(H 3 + ) dense ~ 3.6 ×10 12 cm -2 A V N(H 3 + ) diffuse ~ 4.4 ×10 13 cm -2 A V N total (H 3 + ) diffuse ≈ 100 N total (H 3 + ) dense ζ diffuse ≈ 10 ζ dense Grain neutralization and cosmic ray ionization

The Galactic center The Central Molecular Zone (CMZ) The treasure house of H 3 + Discovery of metastable H 3 + Revelation of warm and diffuse gas Cold 30 K >10 4 cm -3 Hot 10 4 K ~10 2 cm -3 Ultrahot K ~0.3 cm -3 Warm 250 K ~10 2 cm -3 metastable

Deuterium fractionation Destroyers of H 3 + : CO, O…… HD N(H 2 ) =1.5 ×10 6 cm -3 T = 10 K n(H 2 D + ) ≤ n(HD 2 + ) « n(D 3 + ) HD 2 + in prestellar core H 2 D + in protoplanetary disks

Planetary ionospheres Powerful probe of plasmas in planetary Ionosphere from ground based observatories Active driver of thermosphere and ionosphere H 3 + thermostat effect Ion-neutral coupling

Other excitements Recombination → ion pair formation H H – Electron impact rotational excitetion H 3 + cooling in primordial gas H 3 (Hyzone), H 3 –, H 5 +, H 3 + (X) n, H 3 ++ Model calculations, star-forming region diffuse clods H 3 + as electron provider