Single and double Single and double photoionization of Hphotoionization of H

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Single and double Single and double photoionization of H photoionization of H ² ²

Fernando Martín

Departamento de Química, C-9.

Universidad Autónoma de Madrid

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Orion molecular cloud Orion molecular cloud h h ν ν + M + M   M M

⁺⁺

+ e + e

^-^-

M = H

M = H , CO, PAH, … , CO, PAH, …

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P. Lenard, "Über Wirkungen des ultravioletten Lichtes auf gasförmige Körper"

(Effects of ultraviolet light on gaseous substances), Annalen der Physik, 306, 486 (1900)

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“Kinematically complete experiments” give access to fully differential

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Theoretical challenge

• All electronic and vibrational degrees of freedom must be included

• Nearly “exact” quantum description of the correlated motion of electrons and nuclei

• Asymptotic boundary conditions describing

unbound interacting particles must be imposed

exactly

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New physics (even for the simplest H 2

molecule)

– Double photoionization

–

Single photoionization at high energy

– Autoionization Ionization by ultrashort (intense) pulses

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H ₂

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Competing processes

H

₂

( υ ^{= 0) + h} ν

H

₂⁺

( υ ^{) + e}

-

H(nl) + H

⁺

+ e

-

Dissociative photoionization Dissociative photoionization

Photoionization

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H

₂

( υ ^{= 0) + h} ν

H

₂⁺

( υ ^{) + e}

-

H

₂^**

H(nl) + H

⁺

+ e

-

H(nl) + H(n’l’)

Resonant Resonant dissociation dissociation

Dissociative photoionization Dissociative photoionization

Autoionization Autoionization Photoionization

Photoionization Double excitation Double excitation

Competing processes

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H

₂

( υ ^{= 0) + h} ν

H

₂⁺

( υ ^{) + e}

-

H(nl) + H

⁺

+ e

-

Dissociative photoionization Dissociative photoionization

Photoionization Photoionization

H

₂^**

H(nl) + H(n’l’)

Resonant Resonant dissociation dissociation Autoionization

Autoionization

Double excitation Double excitation

H

⁺

+ H

⁺

+ e

-

+ e

-

Double photoionization

Competing processes

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Theory Theory

Dipole approximation (photon wavelength >> size of the molecule)

Adiabatic approximation: the nuclei are much slower than the electrons Relativistic effects are ignored

Semiclassical description of radiation-molecule interaction

1. All electronic and vibrational degrees of freedom are included 1. All electronic and vibrational degrees of freedom are included

2. Equations are solved numerically with B-splines functions or DVR 2. Equations are solved numerically with B-splines functions or DVR

3. Boundary conditions are imposed exactly 3. Boundary conditions are imposed exactly

Full Hamiltonian:

H + D (t )

) (

· ) / ( )

( t e m p A t

D

_i

i

∑

=

∑∑

∑

= = = > = = = >

+

− +

∇

−

∇

−

= ⁿ

i n

i

j ij

N n

i i

N N

n i

i N

r e r

e Z R

e Z Z m

H M

1

2

1 1

2 1

2

1 2 2 1

2 2

2 ˆ 2

α α

α α β α αβ

β α

α α

α



What is new?

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Double ionization: electron correlation in

the continuum

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The problem

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TDCS: changes in correlation due to molecular symmetry TDCS: changes in correlation due to molecular symmetry

Polarization Fixed electron (k

1

)

H

₂

90% energy sharing

24.5eV excess photon energy

He

W. Vanroose, F. Martín, T. N. Rescigno and C. W. McCurdy

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24.5eV excess photon energy

H

₂

Energy sharing

80%

90%

W. Vanroose, F. Martín, T. N. Rescigno and C. W. McCurdy, Science 310, 1787 (2005)

Experiment:

Th. Weber et al, Nature 431, 437 (2004)

Complete photo-induced breakup of the H

2

molecule

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TDCS: changes in correlation due to variations in R TDCS: changes in correlation due to variations in R

Polarization Fixed electron (k

1

)

50% energy sharing

24.5eV excess photon energy at R_eq 15^o between ε and R

W. Vanroose, F. Martín, T. N. Rescigno and C. W. McCurdy Science 310, 1787 (2005)

D. A. Horner, W. Vanroose, F. Martín, T. N. Rescigno and C. W. McCurdy

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The role of autoionizing states

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The problem The problem

e

-

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The role of autoionizing states

F. Martín et al, Science 315, 630 (2007)

H

₂

+ h ν  H(1s) + H

⁺

+ e

^-

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The role of autoionizing states

Low KER region

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The role of autoionizing states

Photon energy = 33 eV

H

₂

+ h ν  H(1s) + H

⁺

+ e

^-

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2

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Two-photon ionization of He

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Two-photon double ionization of He Two-photon double ionization of He

By decreasing order of magnitude L. A. A. Nikolopoulos and P. Lambropoulos, J. Phys. B 40, 1347 (2007)

L. A. A. Nikolopoulos and P. Lambropoulos, J. Phys. B 34, 545 (2001)

E. Foumouo, G. L. Kamta, G. Edah, and B.

Piraux, Phys. Rev. A 74, 063409 (2006) I. A. Ivanov and A. S. Kheifets, Phys. Rev. A 75, 033411 (2007)

B. Piraux, J. Bauer, S. Laulan, and H.

Bachau, Eur. Phys. J. D 26, 7 (2003) L. Feng and H. W. van der Hart, J. Phys. B 36, L1 (2003)

S. X. Hu, J. Colgan, and L. A. Collins, J.

Phys. B 38, L35 (2005)

Experiment: H. Hasegawa, E. J. Takahashi, Y. Nabekawa, K. L. Ishikawa, and K.

Midorikawa, Phys. Rev. A 71, 023407 (2005)

Experiment

D. A. Horner, F. Morales, T. N. Rescigno, F. Martín, and C. W. McCurdy

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Two-photon double ionization of He Two-photon double ionization of He

By decreasing order of magnitude L. A. A. Nikolopoulos and P. Lambropoulos, J. Phys. B 40, 1347 (2007)

L. A. A. Nikolopoulos and P. Lambropoulos, J. Phys. B 34, 545 (2001)

E. Foumouo, G. L. Kamta, G. Edah, and B.

Piraux, Phys. Rev. A 74, 063409 (2006) I. A. Ivanov and A. S. Kheifets, Phys. Rev. A 75, 033411 (2007)

B. Piraux, J. Bauer, S. Laulan, and H.

Bachau, Eur. Phys. J. D 26, 7 (2003) L. Feng and H. W. van der Hart, J. Phys. B 36, L1 (2003)

S. X. Hu, J. Colgan, and L. A. Collins, J.

Phys. B 38, L35 (2005)

Experiment: H. Hasegawa, E. J. Takahashi, Y. Nabekawa, K. L. Ishikawa, and K.

Midorikawa, Phys. Rev. A 71, 023407 (2005)

Experiment

D. A. Horner, F. Morales, T. N. Rescigno, F. Martín, and C. W. McCurdy Phys. Rev. A (Rapid Comm.) 76, 030701 (2007)

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Two-photon double ionization of He

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Two-photon double ionization of He

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Two-photon double ionization of He

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Two-photon double ionization of He

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Two-photon double ionization of He

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Conclusions

• Important role of the nuclear motion to accurately describe fully differential angular distributions in molecular ionization

• Double photoionization of fixed-in-space molecules:

- Dramatic changes in electron correlation with bond length and molecular orientation

• Photon-induced autoionization of fixed-in-space molecules:

- Autoionization can break the g/u molecular symmetry

• First converged two-photon double ionization cross sections of He obtained

• Need for “nearly” exact solutions of the Schrödinger

equation  Possible in Mare Nostrum

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Theory Theory

UAM (Madrid, Spain) I. Sánchez

M. Cortés J. Fernández A. Palacios F. Morales

UBI (Bordeaux, France) H. Bachau

UA (Antwerpen, Belgium) W. Vanroose

LANL (Los Alamos, USA) D. A. Horner

LBNL (Berkeley, USA) T. N. Rescigno

C. W. McCurdy

UNR (Rosario, Argentina) O. A. Fojón

R. D. Rivarola

UA (Medellín, Colombia) J. L. Sanz-Vicario

US (Stockholm, Sweden)

CIRIL (Caen, France) G. Laurent

S. Legendre M. Tarisien L. Adoui A. Cassimi X. Fléchard F. Frémont B. Gervais E. Giglio

J. P. Grandin

LCAM (Orsay, France) M. Lebech

J. C. Houver D. Dowek

Experiment Experiment

UF (Frankfurt, Germany) T. Havermeier

L. Foucar Th. Weber K. Kreidi M. Schöffler L. Schmidt T. Jahnke O. Jagutzki A. Czasch

H. Schmidt-Böcking R. Dörner

LBNL (Berkeley, USA) T. Osipov

A. Belkacem M. H. Prior

KSU (Manhattan, USA) E. P. Benis

C. L. Cocke

AU (Auburn, USA) A. L. Landers

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Perspectives

Chemistry with ultrashort pulses and free Chemistry with ultrashort pulses and free electron lasers (CUSPFEL). Looking for control electron lasers (CUSPFEL). Looking for control

Single and double Single and double photoionization of Hphotoionization of H