•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
79.00x103 78.8078.7078.6078.5078.40
3xh / cm-1
N
O
PR
S
T
Calc.
Exp.
Q
(3+1) REMPI HBr
Simulation:
i(32) <- X(1+)(0,0)
79.00x103 78.8078.7078.6078.5078.40
3xh / cm-1
N
O
PR
S
T
Calc.
Exp.
Q
(3+1) REMPI HBrSimulation:
Be´/ Bf´ = 7.975/7.969 ±0.030cm-1
De´/Df´= (0.55/0.50 ± 0.10)x10-3 cm-1
0 = 78625 ± 2 cm-1
E´(J) = B´J(J+1) – D´J2(J+1)2 0 = E´(v´=0) – E´´(v´´=0) for
i(32) <- X(1+)(0,0)
2P1/2c6s;1g <-<- X 0g
(2+1) REMPI spectra of I2:
(v1,v0)
Fig. 2
Calc. Exp.(2+1) REMPI spectra of I2:as well as Rotational line series:O: J-2 <- J; P: J-1 <- JQ: J <- JR: J+1 <- J; S: J+2 <- J
/ cm-1
2P1/2c6s;1g <-<- X 0g
(v1,v0) =
Fig. 3OP
i.e.:
AB
AB+ + e
AB**
|i1>
|i4>|i3>
|i2>
:
Properties of AB* and AB:- energy configurations- molecular geometries
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
78.2x103 78.178.077.977.877.777.6
3xh / 2xh (cm-1
)
0
013
7
N(J-3)P(J-1) R(J+1)
T(J+3)4
J=6
E(´=0)<-X(´´=0),(0,0)
38
09
0 J=8S(J+2)Q(J)
O(J-2)(2+1)REMPI
(3+1)REMPI
HBr:
16
z
L
NLJL
= 0
Total angular momentum changesFor ´=0 ´´=0:
J:QJ-1;P J+1;RJ-3;N J-2;O J+2;S J+3;T
JJ = 1
J = 1
J = 1
78.2x103 78.178.077.977.877.777.6
3xh / 2xh (cm-1
)
0
013
7
N(J-3)P(J-1) R(J+1)
T(J+3)4
J=6
E(´=0)<-X(´´=0),(0,0)
38
09
0 J=8S(J+2)Q(J)
O(J-2)(2+1)REMPI
(3+1)REMPI
HBr:
J = 1,.. ,n; n = odd; = 0 J = 0 ,2,.. ,n; n = even = 0
16
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
83.0x103 82.982.882.7
3xh / cm-1
R
S
T
Q
P
ON
0
7
4
calc.
exp.HBr, (3+1)REMPI´=3( ´´=0(
18
B´= 8.39cm-1
D´= (0.85x10-3cm-1
0 = 828373 cm-1
2xh3xh
3xh
´=3() ´=2() ´=1() ´=0()
´´=0()
i 1xh 2xh 3xh
“New” state, not detected before:
Predicted state ((23)5d) in this region: L13 (0 = ?????)
“New” state: L13 (0 = 828373 cm-1)
19
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
Complicated spectra, analyses / Example I:
HCl, (3+1) REMPI:
cm-1
3 x (1/=333 nm)
HCl, (3+1) REMPI / Simulation:
cm-1
OK OK???!!
Find “difference spectra” / “exp. – Calc.”
???!!???!!
cm-1
exp. – calc./“Diff.sp.(1)”
“Difference spectra(1)” / “exp. – Calc.”:
exp.
calc.
HCl, (3+1) REMPI
-
3 x (1/=333 nm)
Difference spectra(2) = “exp. – diff. spectra(1)” / Simulation:
“Difference spectra “(1) / Simulation:
58.0x10
3 57.957.857.7
3hcm-1
NO, (3+1)REMPI
D2 X2
REMPI-Current298 K
REMPI-TOFjet cooled
(2,0) -band
Complicated spectra, analyses / Example II:
X 2:
NO
D 2:
z
NL
L
L L
JL
NL
LL
L
JL
z
= 3/2 = 1/2
Spin-rot.interaction
Spin-orbitinteraction
Orbit-rot.interaction
NL
S
NL
S
JLJL
z
E1´
E1´´ E2´´
Av´´=0
Spin-rot.interaction
Orbit-rot.interaction
E2´
Cv´´=0
Cv´
(2,1)
(1,2)(1,1)
(2,2)
4002000-2003h/ cm
-1
three-photon absorptionD<-<-<-X, NON,O,P,Q,R,S,T
(1,1)
(2,1)
(1,2)
(2,2)
"Stick spectrum"
Calc.
, T=298K
(11) (22)
(21)(12)
2
2
(2,0)
57.90x103 57.8557.8057.7557.7057.65
3xh/ cm-1
NO (3+1)REMPI-Current
D2 X
2 simulationT = 298 K
Exp.
Calc.
(2,0)
57.90x103 57.8557.8057.7557.7057.65
3xh/ cm-1
NO, (3+1)REMPI-TOF
D2 X2 simulation
T = 80K
Exp.
Calc.
(2,0)
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
AB
AB+ + e
AB**
|i1>
|i4>|i3>
|i2>
:
State interactions/AB** <->AB#
&dissociation processesAB** -> A# + B#
?
AB#/A#+B#
89.789.689.589.489.389.289.189.0x10
3
HCl(3+1) j3-(0
+) (0,0)
B´=9.654, D´=-0.00039 0=89282
P R
Exp.
Calc.
1357J''=9
0 1 2 34
65 7 89 J''
0 1 2 3=J''
T
HCl; (3+1)REMPIj30
- <- X1+
(0,0)
?
?(3+1)REMPI
j30- <- X1+
(0,0)
Comparison of (2+1) og (3+1)REMPI:
?
92.0x103
91.5
91.0
90.5
E/c
m-1
300250200150100500EJ´,J´+1/cm
-1
5
6
7
8
9
10
11
EJ´,J´+1/cm-1
(2+1)REMPI,HCl(Q)
from (2+1)REMPI,HCl(Q)
from (3+1)REMPI,HCl(R)
5
6
7
8
9
10
11-12.6.2001, HCl,IGOR file:"aHCl(3+1)j3S(0)Calc"AK/PC2
5
V state
j state
(3+1)REMPI
explanation:
State interaction / perturbation j <->V(1+) / interaction strength
v´=24
7
8
Rotational perturbation observed in vibrational band due to the transition2P3/2c5s;1g <-<- X 0g,v1 = 0, v0 = 1
::Because of state interactions:
2P3/2c5s;1g <-> D´(2g)
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
AB
AB+ + e
AB**
|i1>
|i4>|i3>
|i2>
:
Mechanism of nxh absorption / ionization; involvement ofintermediate states.
?
´´=0()
´=0() ´´=0()
P,R: I 12s1 + 3
2s3
N,T: I 32s3
I(N,T) / I(P,R) depend on1
2 and 32 or 1
2 /32
Adjust 12 and 3
2
to obtain best fit:
20
I 12s1 + 3
2s3
21
83.9x103 83.883.783.683.583.483.3
3h/cm-1
TNR
P
Exp.
Calc.
HCl, E(1+) X(1+), (3+1)REMPI
12 /3
2 = 0.900.15
2,,,,,,,,,,,,,,,2
1 43325
1
2,,,,,,,,,,,,23 2
22
´´=0()
´=0()Four
paths:
,,,,
, ,,
,
´´=0()
´=0()
´=1()
23
Paths vs 12 and 3
2 :
0.81
0.36
0.36
0.36
23
,,,
259
,,,
25
81
,,,
25
9
,,,
25
9
,,,1
,,,4
,,,1
,,,1
21 2
323 /
-vs exp.: 12 /3
2 = 0.900.15X(1+):
E(1+)
Major path
,
,,
for HCl:
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
Surface science studies/ collaboration work with J.C. Polanyi, Toronto:
Na
HBr
Na
effect?
i.e.: 1) h + NaBrH(s) -> NaBr(s) + H(g)
Surface science studies/ collaboration work with J.C. Polanyi, Toronto:
Na
effect?
i.e.: 2) h + NaBrH(s) -> Na(s) + HBr#(g)
detect / measure HBr by REMPI: observe kinetic energy.
Surface science studies/ collaboration work with J.C. Polanyi, Toronto:
IREMPIjjiiREMPI ssI 22
)(JNIREMPI
/)(
)(
REMPI
REMPI
IJN
JNI
CJEkTJ
I
kT
JEJJN
REMPI
)(1
)12(ln
))(
exp()12()(
:ondistributiBoltzmann
m/equilibriu at thermal
79.00x103 78.9078.8078.7078.6078.5078.40
2xh/3xh [cm-1
]
29 Q
1 R 10
(2+1)REMPI 10 3P
9S8 O
(3+1)REMPI
T0 8
HBr
2 x (1/=255nm)
3 x (1/=382nm)
(3+1)REMPI simpler spectrum / “more convenient” wavelength
79.00x103 78.8078.7078.6078.5078.40
3xh / cm-1
N
O
PR
S
T
Calc.
Exp.
Q
(3+1) REMPI HBr
-4
-3
-2
-1
0
ln(I
(J)/
S(J)
)
6004002000E(J) / cm
-1
O
P
Q
R
S
T
CJEkTJ
IREMPI
)(1
)12(ln
i.e.:
straight line
(3+1)REMPI spectra and useful to determine N(J)
25oC
Besta beina lína
Line fit
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
V. Blanchet et al., J. Chem. Phys., 119(7), 3751, (2003):
3dF1u+ <-<-<- X1g
+
•Why multiphoton exitations(?); advantages/disadvantages•One color experiments / data
•Experimental methods: Multiphoton ionization (MPI & REMPI)•Data interpretations / theory: “What to see and what not to see(?)”•Results / examples:
- characterization of state properties / energies- (2+1) vs (3+1) REMPI- ”New” states observed- analysis of complicated spectra- state interactions - multi-photon absorption “mechanism”- energy distribution in molecules- polyatomic molecules
•Two color experiments / data
r (A-B)
Ene
rgy
v0
v1
v1-1
v1+1
AB = CdAr:
A30+ <- X10+
(v1,v0)
r (A-B)
Ene
rgy
v0
v1
v1-1
v1+1
AB = I2:
(v1,v0)
2P1/2c6s;1g <-<- X 0g
AB nxh – (/(v1+i,v0)excitations:
nh + AB -> AB*mh + AB -> AB+ + e- (Ekin = 0)
i.e.:
201 EM
nxh
E10
v1
v0
v1 +1
v1 -1
:::
2
01 d
vv
B-O approximation, etc.
I
Exp.
Calc.
E-10 E00 E+10
(v1-1)
(v1)
(v1+1)
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
300
250
200
150
100
50
Inte
nsity
64x103
6260585654Frequency [cm^-1]
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
600
500
400
300
200
100
0
Inte
nsity
64x103
6260585654Frequency [cm^-1]
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
1000
800
600
400
200
0
Inte
nsity
64x103
6260585654Frequency [cm^-1]
V1= 0 1 2 3 4 5V0=0
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
500
400
300
200
100
Inte
nsity
64x103
6260585654Frequency [cm^-1]
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
150
140
130
120
110
100
90
Inte
nsity
64x103
6260585654Frequency [cm^-1]
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
60
50
40
30
20
10
Inte
nsity
64x103
6260585654Frequency [cm^-1]
V1= 0 1 2 3 4 5V0=0
80x103
60
40
20
0
E [c
m-1
]
2.01.81.61.41.21.0R [Å]
6
4
2
Inte
nsity
64x103
6260585654Frequency [cm^-1]
80x103
60
40
20
0
E [cm
-1]
2.01.81.61.41.21.0R [Å]
30x10-3
25
20
15
10
5
0
Inte
nsity
64x103
6260585654Frequency [cm^-1]
V1= 0 1 2 3 4 5V0=0
•Hence: excited states with large(r) internuclear distances cannot easily be accessed in “simultaneous” excitation• Use double resonance technique
Example: Two-colour optical doule resonance (ODR) ionization of I2:
Ene
rgy
I2 X 1S+ g
I2* B 3P0 u
I+I-* 0 g
I2+ + e
r(I-I)
(1+1)REMPI
1´ excitation
((1´+1)+1) REMPI
Ene
rgy
I2 X 1S+ g
I2* B 3P0 u
I+I-* 0 g
I2+ + e
r(I-I)
Please visit: http://www.raunvis.hi.is/~agust/
24
Acknowledgments:Iceland::Benedikt G. Waage, MS student
Jón Matthíasson,
Oddur Ingólfsson, PhD
Kristján Matthíasson, MS student
Victor Huasheng Wang, research scientist
Ágúst Kvaran, professor
24
Funds:•Icelandic Science foundation•University Research Fund•NORFA / NORDPLUS
Collaborators: :Robert J. Donovan, Prof., Edinburgh University, UKTimothy G. Wright, University of Sussex, UKLars Madsen, Aarhus, DenmarkNORFA network participants (?)
Acknowledgments: