Femtosecond Dynamics of Molecules in Intense Laser Fields. CPC2002 T.W. Schmidt 1 , R.B. LópezMartens 2 , G.Roberts 3 University of Cambridge, UK 1. Universität Basel, Confoederatio Helvetica 2. Lunds Universitet, Sverige 3. University of Newcastle, UK. Talk Structure.
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Femtosecond Dynamics of Molecules in Intense Laser Fields
CPC2002
T.W. Schmidt1, R.B. LópezMartens2, G.Roberts3
University of Cambridge, UK
1. Universität Basel, Confoederatio Helvetica
2. Lunds Universitet, Sverige
3. University of Newcastle, UK
Fusion + Fission
research
Unfocussed ns dye laser
Focussed ns dye laser
1 VÅ1
10 VÅ1
109
1010
1011
1012
1013
1014
1015
1016
Wcm2
Focussed ns Nd:YAG
Focussed regen fs laser
It’s the end of
spectroscopy as we know it...
Perturbative
Nonperturbative
D
C (3pp)
A (3ss)
60000
B(P)
40000
Energy (cm1)
X(P)
20000
0
1.0
1.2
1.4
1.6
1.8
2.0
RNO/Å
Weak 90 fs, 800 nm pulses (80 MHz)
fs oscillator
Ar+ laser
PC
scope
Nd: YAG laser
Amplifier
Intense 140 fs, 800 nm pulses (10 Hz)
PMT
KDP xtal
M400 nm
M/C
l/2 plate
0.2 m lens
0.1 m lens
M400 nm
Static cell, NO 1.6 Torr
Intense 100 fs, 400 nm pulses (10 Hz)
Choose basis set
Calculate eigenstates as function of field strength
Propagate time dependent Schrödinger equation by projecting onto time dependent eigenstates
Interpolate eigenstates and eigenvalues from calculations
Evaluate final population in excited state
Spatially integrated SF
0.030
E0(a.u.)
0.000
27250
26160
25070
23980
22890
21800
Frequency/cm1
1.0
0.8
0.6
2

a

A
(2)
0.4
0.2
0.0
0.030
0.025
26400
0.020
25920
0.015
E0(a.u.)
25440
0.010
24960
0.005
24480
0.000
frequency (cm1)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
4  state model
0.030
0.020
E
(a.u.)
0.010
26400
0
25920
25440
0.000
24960
24480
1
frequency (cm
)
1.2
1
0.8
0.6
0.4
0.2
16  state model
0
0.030
0.020
E
(a.u.)
0.010
0
26160
25724
0.000
25288
24852
24416
1
frequency (cm
)
410 nm
10000
405 nm
SF(arb. units)
400 nm
16 state model
4 state model
0
1
2
3
4
5
6
experimental
Peak Intensity (1013Wcm2)
A state shifted out of resonance
by Stark pulse (strong probe)
A state shifted into
resonance by Stark pulse
state energy
400 nm
probe
Unperturbed A state
Ground state
Stark pulse delay
+
Ar
laser
fs oscillator
PC
scope
Regen. Amp.
Nd:YAG laser
400 nm
PMT
800 nm 10 Hz
M/C
MB
to rotary pump
delay stage
NO/Ar mixture
IStark
2.4 TWcm2
3.4 TWcm2
5.8 TWcm2
I400nm = 5.3 TWcm2
fluorescence (arb. units)
7.9 TWcm2
9.9 TWcm2
1.0
0.5
0.0
0.5
1.0
time delay (ps)
3.3 TWcm2
fluorescence (arb. units)
2.5 TWcm2
1.8 TWcm2
I400nm = 27 TWcm2
2.0
1.0
0.0
1.0
2.0
time delay (ps)
4  state model
0.008
0.007
0.008
0.007
0.006
400
400
200
0.006
200
E
(a.u.)
0
0.005
0
S
0.005
200
E
(a.u.)
200
400
S
D
(fs)
0.004
400
0.004
D
(fs)
3  state model
0.011
0.010
0.011
0.009
0.010
400
400
0.009
0.008
200
E
(a.u.)
200
0.008
0
S
0
0.007
E
(a.u.)
0.007
200
200
S
400
0.006
D
(fs)
400
0.006
D
(fs)
NO2*
(A) NO* + O
(X) NO + O
NO2
lpump = 400 nm
lprobe = 800 nm
Ipump 5.3 TWcm2.
Iprobe 0.5; 1.0; 2.0; 4.0 TWcm2.
0.5 TWcm2
0.5 TWcm2
1.0 TWcm2
1.0 TWcm2
v’ = 0 fluorescence
v’ = 1 fluorescence
2.0 TWcm2
2.0 TWcm2
4.0 TWcm2
4.0 TWcm2
1.0
0.0
1.0
2.0
1.0
0.0
1.0
2.0
pumpprobe delay (ps)
pumpprobe delay (ps)
energy
Excited state molecule
and n photons
A,n>
Ground state molecule
and n photons
X,n>
Excited state molecule
and n1 photons
A,n1>
energy
Ground state molecule
and n photons
X,n>
Excited state molecule
and n1 photons
A,n1>
A,n>
2
3ss,n2>
1
3
3ss,n3>
X,n>
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