the role of asymptotic states in h 3 +
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The role of asymptotic states in H 3 +. Jonathan Tennyson Department of Physics and Astronomy Royal Society University College London Jan 2006. HPCx supercomputer: Daresbury Laboratory. Spectroscopy of H 3 +. - PowerPoint PPT PresentationTRANSCRIPT
The role of asymptotic states in H3+
Jonathan TennysonDepartment of Physics and Astronomy Royal Society
University College London Jan 2006
HPCx supercomputer:Daresbury Laboratory
Spectroscopy of H3+
“Solved problem” at low energy
How about near dissociation?• Nature of (rotation-)vibration states?
• Radiative association: H2 + H+ H3+ + h
• Isotope exchange eg HD + H3+ H2 + H2D+
Meilke et al, Phys. Rev. Lett. 91, 063201 (2003)
Accurate H3+
PES
Realistic potential energy surface: Polyansky et al, Mol. Phys., 98, 261 (2000).
r
R
Jacobi coordinates
Density of states: requires serious computer powerEven states
H3+ near dissociation
vibrational state
Calculated rotational constants for H3+
JJ Munro, J Ramanlal & J Tennyson, New J Phys, 7, 196 (2005)
r
R
=90Classical trajectoryat 19600 cm-1
Poincare surface of section at 19600 cm-1
r
p
Classical trajectoryabove dissociation
r
R
=90
“Feshbach” resonance
Poincare surface ofsection for D0 > E > De
Creates H3+ Detects H+
CO2 laser: 800 – 1000 cm-1
H3+ + h H2 + H+
Near-dissociation photodissociation experiment of Carrington et al
Quantum states at dissociation:Near dissociation spectrum of H3
+ by Carrington et al25000+ discrete lines in 222 cm-1
Technique for characterising resonances
1. Solve H0 0 = E 0for all E including > D0.
2. Solve H = H0 + i U(R)
for 0 dropping bound solutions; i U(R) is complex absorbing potential (CAP).
3. Vary to identify resonances in complex plane.
Continuum wavefunction
r
R
= 90
Complex Absorbing Potential (CAP) comparison
Position
Wid
thLocating resonances using a CAP
Vibrational (Feshbach) resonances
Width () > 1 cm-1
Too short lived to be important for photodissociation spectrum
Shape resonances: rotational states trapped by centrifugal barrier
KE release
Complete model of H3+ near-dissociation
photodissocation spectrum
• Vibrational states @ dissociation + above• Rotational states @ dissociation + above• Resonances: lifetime effects• Dipole transitions: spectroscopy
Asymptotic Vibrational States (AVS)
• Robust• Present in other (all?) molecules eg O3, NO2
Bruno Silva Paolo Barletta
James Munro
ChemReactHigh PerformanceComputing Consortium