Fragmentation Dynamics of H2 D2

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Fragmentation Dynamics of H2 / D2 in Intense
Ultrashort Laser Pulses
U. Thumm
B. Feuerstein T. Niederhausen
Kansas State University

• Introduction

• Method of Calculation

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INTRODUCTION
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H2
H2
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Dissociation and Ionization paths
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METHOD OF CALCULATION
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Improved soft-core Coulomb potential
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Dipole oscillator strength for sg su transitions
Kulander et al PRA 53 (1996) 2562
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Array for 2x1D collinear non-BO wave packet
propagation virtual detector method
z electron coordinate R internuclear distance
Grid ?z 0.2 a.u. ?R 0.05 a.u.
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(No Transcript)
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RESULTS
Time evolution of wave function and norm (on
numerical grid)
Evolution of nuclear probability density
r(R,t ) dissociation probability ionization
rate jz(R,t) CE probability
Kinetic energy spectra of the fragments

• Single pulse (I 0.05 0.5 PW/cm2, 25 fs)
• vibrational state and intensity dependence

B) Pump-probe pulses (I 0.3 PW/cm2, 25
fs) CE-imaging of dissociating wave packets
C) Ultrashort pump-probe pulses (I 1 PW/cm2,
5 fs) CE-imaging of bound and dissociating wave
packets
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v 4 0.2 PW/cm2 25 fs
PCE(t)
Dissociation
PD (t)
Laser
Norm(t)
total fragment energy eV
log scale
Contours jz(R,t)
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Norm(t)
v 0 0.2 PW/cm2 25 fs
Laser
PD (t)
PCE(t)
log scale
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v 2 0.2 PW/cm2 25 fs
PCE(t)
PD (t)
Norm(t)
Laser
log scale
Contours jz(R,t)
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v 4 0.2 PW/cm2 25 fs
PCE(t)
Dissociation
PD (t)
Laser
Norm(t)
log scale
Contours jz(R,t)
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PCE(t)
v 6 0.2 PW/cm2 25 fs
PD (t)
Laser
Norm(t)
log scale
Contours jz(R,t)
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PCE(t)
v 8 0.2 PW/cm2 25 fs
Laser
PD (t)
Norm(t)
log scale
Contours jz(R,t)
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Branching ratio Dissociation vs. Coulomb
explosion
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RESULTS II

• Single pulse (I 0.05 0.5 PW/cm2, 25 fs)
• vibrational state and intensity dependence

B) Pump-probe pulses (I 0.3 PW/cm2, 25
fs) CE-imaging of dissociating wave packets
C) Ultrashort pump-probe pulses (I 1 PW/cm2,
5 fs) CE-imaging of bound and dissociating wave
packets
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Pump-probe experiment
D2 target 0.1 PW/cm2 2 x 80 fs variable delay 0
- 300 fs
Trump, Rottke and Sandner PRA 59 (1999) 2858
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Pump-probe (D2) v 0 0.3 PW/cm2 2 x 25 fs
delay 30 fs
Norm(t)
PCE(t)
Dissociation
Coulomb explosion
Laser
PD (t)
- - - - - (Coulomb only)
log scale
Contours jz(R,t)
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Pump-probe (D2) v 0 0.3 PW/cm2 2 x 25 fs
delay 50 fs
Norm(t)
PCE(t)
Dissociation
Coulomb explosion
PD (t)
Laser
- - - - - (Coulomb only)
b
c
a
log scale
Contours jz(R,t)
c
b
a
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Pump-probe (D2) v 0 0.3 PW/cm2 2 x 25 fs
delay 70 fs
Norm(t)
PCE(t)
Dissociation
Coulomb explosion
Laser
PD (t)
- - - - - (Coulomb only)
b
c
a
log scale
Contours jz(R,t)
c
b
a
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RESULTS III

• Single pulse (I 0.05 0.5 PW/cm2, 25 fs)
• vibrational state and intensity dependence

B) Pump-probe pulses (I 0.3 PW/cm2, 25
fs) CE-imaging of dissociating wave packets
C) Ultrashort pump-probe pulses (I 1 PW/cm2,
5 fs) CE-imaging of bound and dissociating wave
packets
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Time evolution of a coherent superposition of
states
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autocorrelation
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Coulomb explosion imaging of nuclear wave packets
Fragment yield Y at Ekin Y(Ekin) dEkin
?(R)2 dR ? Y(Ekin) R 2 ?(R)2
1/R
d d
Probe
?(R,t)2
R
D2
Pump
D2
initial ?(R)2
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?(R)2 reconstruction from CE fragment kin.
energy spectra
moving wave packet
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?(R)2 reconstruction from CE fragment kin.
energy spectra
turning point
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?(R)2 reconstruction from CE fragment kin.
energy spectra
? 40 fs
?(R)2
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?(R)2 reconstruction from CE fragment kin.
energy spectra
revival