iphoton exitations(?); advantages/disadvantages r experiments / data imental methods: Multiphoton ionization (MPI & REMP interpretations / theory: “What to see and what not ts / examples: racterization of state properties / energies 1) vs (3+1) REMPI w” states observed lysis of complicated spectra te interactions ti-photon absorption “mechanism” rgy distribution in molecules yatomic molecules r experiments / data
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Why multiphoton exitations(?); advantages/disadvantages One color experiments / data
II. Multi- photon excitation / ionization processes. 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: - PowerPoint PPT Presentation
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•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
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
•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
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:
•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 (?)