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Vladimir Roudnev and B.D. Esry

HD + Photodissociation in an Ultrashort Infrared Laser Pulse: Carrier-Envelope Phase Difference Effects. Vladimir Roudnev and B.D. Esry.

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Vladimir Roudnev and B.D. Esry

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  1. HD+ Photodissociation in an Ultrashort Infrared Laser Pulse: Carrier-Envelope Phase Difference Effects Vladimir Roudnev and B.D. Esry The work is supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, Us. Department of Energy, and by the Research Corp.

  2. Could any asymmetry be observed in HD+ photodissociation? How to treat dissociation processes in the presence of ionization? What kind of asymmetries might be expected? Motivation

  3. 3D model (1 nuclear+2 electron degrees of freedom) of the HD+ ion in a laser field Numerical solution of the time-dependent Schroedinger equation (TDSE) The HD+ ion in the field of intense (4× to 9×1014W/cm2) 10fs linearly polarized 790 nm laser pulse: calculation results Carrier-envelope phase effects observability for reaction probabilities Fragments' velocity distribution in scaled coordinate approach Carrier-envelope phase effects observability for fragments' velocity distributions Topics

  4. E Coordinate system for HD+ molecule Intrinsic coordinates: xe ye

  5. Time-dependent Schroedinger equation

  6. Cayley approximant The time evolution • Operator splitting

  7. Single and double-scale approximants Partial approximants Single-scale approximant Double-scale approximant

  8. Ionization probabilities intensity dependence

  9. z H+d M R p+D Channel separation: domains in the configuration space Different channels can be identified by the corresponding domains in the configuration space

  10. Electron density distribution I=8 1014 W/cm2 CEPD=π H+d channel dominates I=8 1014 W/cm2 CEPD=0 D+p channel dominates z (a.u.) z (a.u.) t (a.u.) t (a.u.)

  11. Dissociation probabilities phase dependence

  12. Laser phase averaged dissociation probabilities

  13. I=6×1014 W/cm2 I=7×1014 W/cm2 I=8×1014 W/cm2 I=9×1014 W/cm2 Orientation averaged dissociation probabilities

  14. The dissociation asymmetry observability • Controlled carrier-envelope phase difference • Oriented molecules Channel asymmetry is revealed in total dissociation • Controlled carrier-envelope phase difference • Not oriented molecules Channel asymmetry is revealed in spatial distribution of dissociated fragments • Uncontrolled carrier-envelope phase difference No channel asymmetry is expected

  15. Scaled coordinates approach

  16. Scaled coordinate approach: properties • Bound states shrink with time • Continuum states approach a stationary distribution at large times • Momentum distribution of the continuum part can be obtained from the asymptotic stationary state by simple rescaling • Continuum states converge to the rescaled momentum distribution faster than O(R(t)-3/2) Rescaling:

  17. t=0 t=1500 t=5 t=2500 t=10 t=3500 Scaled coordinates distribution converges to momentum distribution Bound state in a laser field Free particle

  18. Fragment velocity distribution CEPD variation CEPD/π H velocity (au) D velocity (au)

  19. Orientation averaged fragment velocity distribution CEPD variation CEPD/π H velocity (au) D velocity (au)

  20. CEPD effects for the fragments of fixed velocity

  21. Summary • Strong CEPD effects are expected for dissociation of the HD+ molecule in 10 fs 785 nm laser pulse • Reaction asymmetries can be observed only if the laser CEPD is controlled, charged and neutral reaction fragments must be registered separately • The effect is much stronger if fragment velocity selection is performed

  22. Future • What are the velocity distributions for ionization? • How the initial state affects the results? • How to improve the accuracy/perfomance?

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