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 +.

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The role of asymptotic states in H 3 +

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The role of asymptotic states in h 3

The role of asymptotic states in H3+

Jonathan Tennyson

Department of Physics and Astronomy Royal Society

University College London Jan 2006

HPCx supercomputer:

Daresbury Laboratory


Spectroscopy of h 3

Spectroscopy of H3+

Meilke et al, Phys. Rev. Lett. 91, 063201 (2003)

“Solved problem” at low energy

How about near dissociation?

  • Nature of (rotation-)vibration states?

  • Radiative association: H2 + H+ H3+ + hn

  • Isotope exchange eg HD + H3+  H2 + H2D+


The role of asymptotic states in h 3

Accurate H3+

PES

Realistic potential energy surface:

Polyansky et al, Mol. Phys., 98, 261 (2000).

R

q

r

Jacobi coordinates


Density of states requires serious computer power

Even states

Density of states: requires serious computer power


H 3 near dissociation vibrational state

H3+ near dissociation vibrational state


The role of asymptotic states in h 3

Calculated rotational constants for H3+

JJ Munro, J Ramanlal & J Tennyson, New J Phys, 7, 196 (2005)


The role of asymptotic states in h 3

Classical trajectory

at 19600 cm-1

q=90

R

r


Poincare surface of section at 19600 cm 1

Poincare surface of section at 19600 cm-1

p

r


Classical trajectory above dissociation

Classical trajectoryabove dissociation

q=90

R

“Feshbach” resonance

r


The role of asymptotic states in h 3

Poincare surface of

section for

D0 > E > De


The role of asymptotic states in h 3

CO2 laser: 800 – 1000 cm-1

Detects H+

Creates H3+

H3+ + hn H2 + H+

Near-dissociation photodissociation experiment

of Carrington et al


The role of asymptotic states in h 3

Quantum states at dissociation:

Near dissociation spectrum of H3+ by Carrington et al

25000+ discrete lines in 222 cm-1


Technique for characterising resonances

Technique for characterising resonances

  • Solve H0F0 = E F0for all E including > D0.

  • Solve H = H0 + il U(R)

    for F0 dropping bound solutions;

    i U(R) is complex absorbing potential (CAP).

    3. Vary l to identify resonances in complex plane.


Continuum wavefunction

Continuum wavefunction

q= 90

R

r


The role of asymptotic states in h 3

Complex Absorbing Potential (CAP) comparison


The role of asymptotic states in h 3

Locating resonances using a CAP

Width

Position


Vibrational feshbach resonances

Vibrational (Feshbach) resonances

Width (G) > 1 cm-1

Too short lived to be important for photodissociation spectrum


Shape resonances rotational states trapped by centrifugal barrier

Shape resonances: rotational states trapped by centrifugal barrier

KE release


Complete model of h 3 near dissociation photodissocation spectrum

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


The role of asymptotic states in h 3

ChemReact

High Performance

Computing Consortium

Paolo Barletta

Bruno Silva

James Munro


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