ultrafast laser interactions

AMP Talk June 2004

Intense Field Femtosecond Laser Interactions

Ultrafast Laser Interactions

with atoms, molecules, and ions

Jarlath McKenna

Supervisor: Prof. Ian Williams

AMP Talk June 2004


The Experiment….

QUB Ion Beam Apparatus

AMP Talk June 2004


The Experiment….


B

IonsMagnet

Aperture

AMP Talk June 2004


The Experiment….


AMP Talk June 2004


The Experiment….

UCL Neutral Target ApparatusFocussed Laser Beam

AMP Talk June 2004


and scanning techniques….

z

x

y

Intensity Scan

focussed laser direction

ion beam direction

AMP Talk June 2004


and scanning techniques….

z

x

y

Intensity Selective Scan

focussed laser direction

ion beam direction

AMP Talk June 2004


…Sequential ionization

Walker et al PRL, 73, 1227 (1994)

AMP Talk June 2004


S

…Sequential ionization

Walker et al PRL, 73, 1227 (1994)

AMP Talk June 2004


SNS

…Nonsequential ionization

Walker et al PRL, 73, 1227 (1994)

AMP Talk June 2004


-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Z Position (mm)

Sig

nal (

arb.

)

Linear

Circular

…Xe results!!

Xe → Xe+

AMP Talk June 2004


-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Sig

nal (

arb.

)

Z Position (mm)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Z Position (mm)

Sig

na

l (a

rb.)

Linear

Circular

…Xe results!!

Xe → Xe2+

Xe+ from Xe

AMP Talk June 2004


Sig

nal (

arb.

)

Z Position (mm)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Z Position (mm)

Sig

na

l (a

rb.)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Sig

na

l (a

rb.)

Linear

Circular

…Xe results!!

Xe → Xe3+

Xe+ from Xe

Xe2+ from Xe

AMP Talk June 2004


Sig

nal (

arb.

)

Z Position (mm)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Z Position (mm)

Sig

na

l (a

rb.)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Sig

na

l (a

rb.)

Sig

na

l (a

rb.)

Linear

Circular

…Xe results!!

Xe+ → Xe3+Xe2+ from Xe

Xe3+ from Xe

Xe+ from Xe

AMP Talk June 2004


Sig

nal (

arb.

)

Z Position (mm)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Z Position (mm)

Sig

na

l (a

rb.)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Sig

na

l (a

rb.)

Sig

na

l (a

rb.)

Linear

Circular

…Xe results!!

Xe2+ → Xe3+

Xe+ from Xe

Xe2+ from Xe

Xe3+ from Xe

Xe3+ from Xe+

AMP Talk June 2004


Sig

nal (

arb.

)

Z Position (mm)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Z Position (mm)

Sig

na

l (a

rb.)

-15 -10 -5 0 5 10 15

0.0

0.2

0.4

0.6

0.8

1.0

Sig

na

l (a

rb.)

Sig

na

l (a

rb.)

-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50

0.0

0.2

0.4

0.6

0.8

1.0

Linear

Circular

…Xe results!!

Xe+ → Xe2+

Xe+ from Xe

Xe2+ from Xe

Xe3+ from Xe

Xe3+ from Xe+

Xe3+

from Xe2+

AMP Talk June 2004


Vibrational Trapping in H2+?

0

1

2

3

1sg

2pu

Internuclear separation R (a.u.)1 2 3 4 5 6 7 8 9 10

0

-1

-2

-3

-4

-5

Fie

ld-d

ress

ed p

oten

tial e

nerg

y (e

V)

v = 0

v = 9

v = 5v = 4v = 3

H neutrals from H2+

AMP Talk June 2004


…So what’s next??

Position Sensitive Detector

resolve vibrational levels of H2+

Cool vibrational levels of H2+

electrostatic ion trap

electric quadrupole

Shorter pulses (~10 fs)hollow fibre (gas cell)freeze vibrational motion

Frequency double laser (i.e. 800nm → 400nm)larger shift of photon dressed states of H2

+

ultrafast laser interactions

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