Transcript No Slide Title

Gas phase electronic spectra of
linear carbon chains:
HCn+1H, HCnH , HCn+1 , HCn
Felix Güthe1,
Hongbin Ding, Thomas Pino3,
Tim W. Schmidt4, Andrei Boguslavskiy
John Maier
Institut für Physikalische Chemie der Universität Basel, Basel, Switzerland
1 abcd Switzerland Ltd., Baden, Switzerland
2 Institut für Physikalische Chemie der Universität Basel, Basel, Switzerland
3 Laboratoire de Photophysique Moleculaire, Universite Paris-Sud, Orsay, France
4 Sydney University, Sydney, Australia
Bunsentagung , Dresden 2004
Nanowires
hypothetical new allotrope
molecular wire
precursor nano tubes, fullerenes etc.
interstellar molecules
hypothetical new allotrope
diamond:
sp3
graphite:
sp2
“polyyne”:
sp
optical properties:
transition n-> ∞∞
band gap bulk behaviour
optical properties:
band gaps
absorption in the ISM
->spectroscopy
taken from:
http://cfa-www.harvard.edu/cfa/mmw/mmwlab/ismmolecules_organic.html
Interstellar molecules
Flames
K.-H. Homman, Angew. Chem. 1998, 110, 2572; Angew. Chem. Int. Ed. Engl. 1998,
37, 2435;
Pulsed Electrical Discharge
Picture : H. Linnartz
Experiment
Resonant Two Photon Ionization Spectroscopy
1
1% C 2H2 in Ar
+
- Cn
p ~ 10 bar
U
2
Cn+ + e 2 fixed
Cn*
 1 scanned
C n+
2= 157 nm, 189nm, 212nm
Cn
Mass spectrum
C4H2- Discharge source
C10
C20
C30
C40
C50
C60
C70
C80
C90
C100
C110
0
C114
Intensity
-2
C60
C44
C24
-4
C25
-6
C4H2
C24Hm
-8
120
240
360
480
600
720
840
Masse (a.m.u.)
960
1080
1200
1320
electronic transitions- HC2nH
HC2nH
(4n)s
(n+ 1)p
S- S
S- D
(n)p
(4n-1)s
excitations: 1S+g
→→
(n)pu/ (n-1)pg →→ (n)pg/u:
(n)pu/ (n-1)pg →→ (n)pg/u:
(n)pu/ (n-1)pg →→ (4n)sg/u :
(4n-1)sg/u
→→ (n)pg/u:
(n-1)p
1 +
XS
g
~
2
4
2
4
4
(2n)sg (n-1)pg (n)pu for n = even
4
(2n)su (n-1)pu (n-1)pg for n = odd
levels have alternating symmetries g and u
A1Du
B1S+u
1P
u
1P
u
R2CPI-spectra of acetylenic chains
HC2nH(n=8-13): 1S+g
→→1S+u
HC26H
HC24H
HC22H
HC20H
HC18H
HC16H
280
290
300
310
320
330
Wavelength (nm)
340
350
360
D states: HC6H, HC8H, HC10H, HC12H, HC14H
HC2nH(n=3-7):1S+g→→1Du, 1S-u dipole-forbidden (np bending)
280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440
1
170
HC14H
1
HC12H
1
40 140
1
1
HC10H 30140
1 1
1
4060140
2
1
140160
1
1
140
1
140
1
20120
HC8H
1
120
1
80
HC6H
280 290 300 310 320 330 340 350 360 370 380 390 400 410 420 430 440
Wavelength (nm)
Observed and Calculated Values
12
HC2nH
1
Transition energy (eV)
1
+
C Pu-X Sg (CASSCF)
10
1
1
+
C Pu-X Sg (Exp.)
8
1
+
1
+
B Su -X Sg (CASSCF)
6
1
+
1
+
B Su -X Sg (Exp.)
4
2
1
1
1
1
-
1
+
A Du( Su )-X Sg (CASSCF)
+
A Du-X Sg (Exp.)
0
0
4
8
12
16
20
24
28
Number of carbon atoms
strong B-transiton!
electronic transitions- HC2n+1H
HC2n+ 1H
(4n)s
(n+ 1)p
excitations: 3S-g
(n-1)pg/ (n-1)pu
(n)pu/ (n-1)pg
(n)pu/ (n-1)pg
→→
→→ (n)pu/ (n-1)pg: a3S-u
→→ (n)pg/u:
b3S-u
→→ (4n+4)sg/u : C3Pu
(n)p
(n-1)p
(4n-1)s
1 -
XSg ~
2
4
2
4
2
(2n)sg (n-1)pg (n)pu for n = even
mixing of degenerate a(3S-u) and b(3S-u)
yields
A(3S-u )=
a+b/sqrt(2)
B(3S-u )=
a-b/sqrt(2)
2
(2n)su (n-1)pu (n-1)pg for n = odd
levels have alternating symmetries g and u
Dewar-Longuet-Higgins (1954, Proc. Phys. Soc.) on odd
alternant hydrocarbons:
• A occurs at longer wavelength and is weaker than B
• B must be the strongest transition
2
2
30
3
30
*
*
2
30 *
1
1
*
HC11H
00
*
750
0
00
0
*
725
700
675
40
30
30
*
0
00
1
40
HC13H
650
625
600
575
550
525
500
475
450
The HC2n+1H Series: HC7H, HC9H, HC11H, HC13H
HC2n+1H(n=3-6): X 3S-g →→ A 3S-u,
HC9H
*~ fragment: HC9H2-H
1
0
20
00
0
1
20+2nb
1
1
40
1
20+40
23000
22000
21000
20000
19000
18000
2nb
00
1'
2'
2na
17000
-1 16000
Wavenumber (cm )
15000
HC7H
3'
14000
13000
HC13H ... HC19H: X 3S-g →→ B 3S-u,
28800
29000
29200
29400
29600
29800
30000
30200
0
00
HC19H
strong B-transiton
HC19H is weak in mass spectrum,


but still visible
0
00
HC13H
C-X (CASSCF)
10
C-X (MRCI)
9
35000
35200
35400
35600
35800
-1
Wavenumbers (cm )
36000
36200
Transition energies (eV)
34800
8
7
B-X (CASSCF)
6
B-X (MRCI)
5
3
-
3
-
B Su -X Sg (Gas phase)
A-X (MRCI)
4
A-X (CASSCF)
3
-
3
-
A Su -X Sg (Matrix & gas phase)
3
2
5
MRCI: Mühlhäuser, Peyerimhoff et al. (2002)
7
9
11
13
15
Number of carbon atoms
17
19
HC13H ... HC19H: X 3S-g →→ B 3S-u,
12
B-X (CASSCF)
Oscillator strength
10
8
6
B-X (MRCI)
4
A-X (MRCI)
C-X (CASSCF)
2
X1000
A-X (CASSCF)
X100
X100
X1000
0
C-X (MRCI)
5
7
9
11
13
15
Number of carbon atoms
as predicited in 1954 !
17
19
extrapolation to C
HC2nH (even):
70000
1 + 1 -
1 +
Du, Su¬ Sg:
-1
60000
E (cm )= 17100+97004/N ~585nm
1 +
1 +
Su ¬ Sg :
-1
E (cm )= 20068+244590/N ~498nm
-1
E (cm )
50000
40000
30000
20000
HC2n+1H (odd):
3 -
3 -
Su¬ Sg:
-1
E (cm )= 7152+89094/N ~1398nm
3 3 Su¬ Sg:
10000
-1
E (cm )= 17608+232392/N ~567nm
0
 60
56
52
48
44
40
36
322824 20
16
12
8
Ncarbon
4
isoelectronic HCn- system
-
HC2n (even):
HC2nH (even):
1 + 1 -
70000
3 -
3 -
Su¬ Sg: ac
1 +
Du , S u ¬ S g :
-1
-1
E (cm )= 17100+97004/N ~585nm
1 +
1 +
Su¬ Sg:
-1
E (cm )= 20068+244590/N ~498nm
60000
E (cm )= 4926+259048/N ~2030nm
3 3 Su¬ Sg: cum
-1
E (cm )= 10096+182895/N ~990nm
1 +
1 +
DBS: Su¬ Sg:
-1
E (cm )= 34262-22591/N ~292nm~EA
-1
E (cm )
50000
40000
-
HC2n+1 (odd):
30000
3 -
3 -
Su¬ Sg: ac
-1
E (cm )= 8009+178096/N ~1248nm
3 3 Su¬ Sg: cum
20000
-1
E (cm )= 14783+129569/N ~676nm
HC2n+1H (odd):
3 -
3 -
Su¬ Sg:
10000
-1
E (cm )= 7152+89094/N ~1398nm
3 3 Su¬ Sg:
-1
E (cm )= 17608+232392/N ~567nm
0
 60
56
52
48
44
40
36
322824 20
16
12
8
Ncarbon
4
Solvent and endgroup effect
45000
40000
-1
E (cm )
35000
HC2nH (even)1S+u¬1S+g: ?
30000
gasphase:
-1
E (cm )= 20068+244590/N ~498nm
Ne-Matrix :
-1
E (cm )= 19000+241578/N ~526nm
methanol:
-1
E (cm )= 16885+237195/N ~592nm
acetonitril:
-1
E (cm )= 18905+195460/N ~528nm
25000
20000
15000
 6056524844403632 28
24
20
16
12
Ncarbon
8
Conclusions

for odd and even chains: strong B-states:
–
–
–
–
–



f~Nc
position in the visible
broad peaks
in the ISM
similar for kation (HC2n+1H+, HC2n+1H-), anion
sp allotrope: bandgap in UV/visible
matrix shifts
bondlength alternation
HC2n+1H: anion - neutral- cation
ground state: (n-1)p4(n)p1,2,3 (n+1)p0 :
Ions:
+ ,0,HC2n+ 1H
(4n)s
(n+ 1)p
(n)p
(n-1)p
(4n-1)s
1 -
XSg ~
2
4
2
4
1,2,3
(2n)sg (n-1)pg (n)pu
for n = even
1,2,3
(2n)su (n-1)pu (n-1)pg
for n = odd
(n-1)p4(n)p1,2,3 →→ (n-1)p3(n)p2,3,4 :
a3S-u
(n)p1,2,3 (n+1)p0 →→(n)p0, 1,2 (n+1)p1 :
b3S-u
same behaviour for anions and cations:
a and b degenerate-> mixing to yield
 weak A and
 strong B transition
Bond length alternation:
Acetylenic vs cumulenic
Bond length alternation in the polyacetylenic chains:
1.36
even:
HC10H
HC26H
"single"
Ethene
odd:
C9
Bond length (Å)
1.34
1.32
Allene
1.30
1.28
1.26
1.24
1.22
Ethine
"triple"
1.20
0
1
2
3
4
5
6
7
C-C bond
8
9
10
11
12
13
Bond length alternation:
even and odd
Bond length alternation in the polyacetylenic chains:
1.36
even:
HC10H
HC26H
"single"
Ethene
odd:
HC13H
C9
Bond length (Å)
1.34
1.32
Allene
1.30
1.28
1.26
1.24
1.22
Ethine
"triple"
1.20
0
1
2
3
4
5
6
7
C-C bond
8
9
10
11
12
13
Bond length alternation:
neutral and anionic
Bond length alternation in the polyacetylenic chains:
1.36
even:
HC10H
HC26H
"single"
Ethene
HC10
-
odd:
1.34
Bond length (Å)
HC13H
HC9
C9
1.32
Allene
1.30
1.28
1.26
1.24
1.22
Ethine
"triple"
1.20
0
1
2
3
4
5
6
7
C-C bond
8
9
10
11
12
13
-
backup longchains

additional material
Spectroscopic techniques


Spectral range: UV/visible for DIBs
Direct absorption
– I/I0
– sensitivity and selectivity
– multiple passes and Cavity Ring Down Spectroscopy
or

Laser induced Fluorescence
• excited state lifetime, fluorescence quantum yield

Mass selective techniques
– Resonance Enhanced Multi Photon Ionisation (and related R2ColourPhotoDetachment)
– change in the m/z ratio (anion  neutral ; neutral  cation ,
cation  Fragment)
– sensitivity for ion detection is high!
– additional molecular information: mass
– physics of the ionisation/detachment process is important
REMPI scheme
Cn+
Cn*+ Cn-m+ +Cm
Ion:D0
Cn* Cn-m +Cm
IP
UV
S1
exit channels?
IP/2
near UV
near UV
S1
vis
Neutral:S0
common example:
“uncommon Example”:Cn
2 colour scheme for
Excitation scheme [1+1']
REMPI on polyacetylenes
14
FranckCondon
factors
12
2
X ( Pu)
cation
10
Energie (eV)
VUV Ionisation
8
1 +
B( Su )
1 -
1
A ( S u; Du)
6
IC ~ ns
IC < ps
1 +
4
2
X( Sg )
IP
UV Excitation
even
0
R
odd
Solvent shifts
40000
Neon Matrix
Gas phase
Methanol
38000
1 +
1 +
HCnH: Su ¬ Sg
-1
Wavenumbers (cm )
36000
34000
strong solvent shift:
4000 cm-1 to the red
32000
30000
28000
-1
26000
10
Gas - matrix ~1300 cm
-1
Gas - solvent ~3500 cm
12
14
16
18
20
22
24
26
28
Bond length alternation in the polyacetylenic chains:
HC26H and HC10
1.40
"single"
1.38
Bond length (Å)
1.36
HC26H
HC10
Ethene
HC
C
HC
C
-
HC2n-
1.34
1.32
Allene
1.30
+
HC
CH
1.26
HC
CH
1.24
HC
+
CH
1.28
C
1.22
"triple"
Ethine
1.20
0
5
10
15
C-C bond
20
25
HC2nH
Bond length alternation in the polyacetylenic chains:
HC10H and HC10
1.40
HC10H
1.38
1.36
Bond length (Å)
HC10
"single"
-
B3LYP
MP2
Ethene
1.34
1.32
Allene
1.30
1.28
1.26
1.24
1.22
"triple"
Ethine
1.20
0
1
2
3
4
5
6
C-C bond
7
8
9
10
R2CPI-spectra of acetylenic chains
1S+
g
→→1S+u
HC26H
HC24H
HC22H
HC20H
HC18H
HC16H
280 290 300 310 320 330 340 350 360
Wavelength (nm)
Even D: HC6H, HC8H, HC10H, HC12H, HC14H
HC2nH(n=3-7): 1S+g →→1Du
1
170
HC14H
380
390
1
HC12H
350
360
3302
HC8H
290
2
0
1
80
290
410
1
1
1
380
1
1
120
1
420
430
140
390
400
350
360
370
380
zoom
300
310
300
410
1
140
1
30 140
340
440
1
140 160
40 60 140
320
280
400
370
1
HC10H
HC6H
1
40 140
320
310
Wavelength (nm)
330
320
1
120
340
330
340
The HC2n+1H Series:
HC7H, HC9H, HC11H, HC13H ... HC19H
8
1
HC7H
3'
19000
3
24
2'
1'
19500
20000
20500
1
*
17000
HC13H
13000
18000
19000
*
*
20000
3
2
1
15000
21000
2
HC9H
HC11H
5
16000
17000
15000
16000
10
9 11
21500
22000
*3
*
*
*
5 21000
4
19000
-1
Wavenumber (cm )
23000
23000
7
6
21000
4
17000
22500
22000
20000
2
3
1
14000
18000
6
7
22000
5
18000
19000
600
550
500
-
CNH
Wavelength (nm)
450
400
350
HC2nH
300
250
Neutral
1
1
HC2nH
: S+¬ S+
u
g
Anions
1 +
1 +
Ac. HC2n : S ¬ S
200
150
100
0
2
4
6
8 10 12 14 16 18 20 22 24 26 28
Number of carbon atoms
600
550
500
CNH
-
Wavelength (nm)
450
400
350
HC2nH
300
250
200
150
Neutral
1 +
1 +
HC2nH
: Su ¬ Sg
Anions
1 +
1 +
Ac. HC2n : S ¬ S
Cum. HC2n
-
-
3 -
- 1
100
3 -
Ac. HC2n-1 : S ¬ S
1
Cum. HC2n-1 : A'¬ A'
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Number of carbon atoms
end polayacetylenes

additional material
Gas phase electronic spectra of linear
carbon chains:
HCn+1H, HCnH , HCn+1 , HCn
Felix Güthe1,
Hongbin Ding, Thomas Pino3,
Tim W. Schmidt4, Andrei Boguslavskiy
John Maier
Institut für Physikalische Chemie der Universität Basel, Basel, Switzerland
1 abcd Switzerland Ltd., Baden, Switzerland
2 Institut für Physikalische Chemie der Universität Basel, Basel, Switzerland
3 Laboratoire de Photophysique Moleculaire, Universite Paris-Sud, Orsay, France
4 Sydney University, Sydney, Australia
Bunsentagung , Dresden 2004
C3H- identified in the ISM by
microwave spectroscopy!
540
520
500
480
460
440
420
400
380
nm
360
C3D
C10
C3H
-1
cm

spectrum in the visible detected via
R2CPI with F2 laser in the VUV !!
C3H
2
2
2
close-up 40 band
A A'(K'=2)--X P 1/2
3
40
2
2
A A'(K'=2)--X P 3/2
20910
Intensity (a.u.)
20880
2
40
1
P
-- X
2
'
2
AA
1/2
1
40
XP
''
2
BA
2
40
1/2
0
00
0
00
19000
complicated
20000
21000
spectrum!
Renner-Teller (4 atoms) distorted
more than one electronic state
-1
22000 cm
C3H
6.5
6.0
ground
5.5
5.0
4.5
2
4.0
Energy (eV)
state: 2P
linear-bend transition
3 electronic states
contribute to spectrum
complicated RennerTeller distorted spectrum!
individual lines to weak
to be detected in the ISM
by vis-absorption
2 +
S
S
3.5
2 -
3.0
2
2.5
D
2.0
1.5
1.0
6 .5
0.5
6 .0
5 .5
2
P
0.0
60 80 100 120 140 160 180 200 220 240 260 280 300
5 .0
E n e r g y (e V )
P
F
4 .5
4 .0
3 .5
2
P
2
S
S
2
3 .0
2
2 .5
E
+
D
-
C
D
B
A
2 .0
1 .5
CCH angle°
1 .0
0 .5
X
2
0 .0
6 0
8 0
P
1 0 0 1 2 0 1 4 0 1 6 0 1 8 0 2 0 0 2 2 0 2 4 0 2 6 0 2 8 0 3 0 0
C C H
a n g le °
electronic transitions- C2nH
ground state
C2nH for n>2
ground state
C2nH for n<2
(4n+2)s
(4n+ 2)s
(n+1)p
(n+1)p
(n)p
(4n+1)s
(4n+1)s
(n)p
(n-1)p
(n-1)p
2
X P~
2
4
2
3
(n-1)p (4n+1)s (n-1)p
X S~ for n < 2
4
4
1
(n-1)p (n)p (4n+1)s
excitations: 2P →→
(4n+1)s →→ (n)p:
(n-1)p →→ (n)p:
(n)p
→→ (n+1)p:
2S :weak, IR
2P :strong, vis
2P :weak UV
excitations: 2S →→
(n)p
→→ (4n+1)s : 2P
(4n+1)s →→ (n+1)p : 2P
(n)p
→→ (n+1)p : 2S
The C2n+1H Series: C3H,C5H,C7H,C9H
2
2
2
F P --X P
00
C9H
2
D P --X P
70
0
110
1
1
00
00
0
2 +
2
C S --X P
0
2
2
A D --X P
2 -
2 +
Intensity (a.u.)
B S --X P
00
C7H
00
0
2 -
130
00
C5H
2
2
C A'' --X P
00
100
C3H
2
1
1
2
90
00
1
0
2
2
00
420
0
A D --X P
0
B A'' --X P
390
0
0
2
360
00
2
B S --X P
100
2
C S --X P
2
450
480
2
2
A A' --X P
0
00
510
0
540
570
600
nm
electronic transitions- C2n+1H
C2n+1H
(4n+ 4)s
excitations: 2P →→
(4n+3)s →→ (n)p:
(n-1)p →→ (n)p:
(n)p
→→ (n+1)p:
(n+1)p
(n)p
(4n+3)s
(n-1)p
2
X P~
4
2
1
(n-1)p (4n+3)s (n)p
2D, 2S-, 2S+:vis
2P : vis
2P :
The C2n+1H Series: C3H,C5H,C7H,C9H
2
2D, 2S-, 2S+, 2P -
→→
3- 4 different electronic
states!
00
C9H
2
D P --X P
2
70
0
110
1
1
00
00
0
2 +
2
C S --X P
0
2
2
A D --X P
2 -
2 +
00
C7H
00
0
2 -
130
00
C5H
2
2
C A'' --X P
00
100
2
2
1
90
2
00
1
0
2
2
00
420
0
1
A D --X P
0
B A'' --X P
390
0
0
C3H
360
00
2
B S --X P
100
2
C S --X P
2
B S --X P
Intensity (a.u.)
2P
2
F P --X P
450
480
2
2
A A' --X P
0
00
510
0
540
570
600
nm
Extrapolation
25000
HC2n+1(odd):
-1
E (cm )
20000
2
2
A D¬ P
15000
2 -
2
B S¬ P
2 +
2
C S¬P
HC2n(even):
10000
2
2
P¬ P:
-1
E (cm )= 6830+72144/N ~1464nm
5000
 60
57
54
51
48
45
42
39
36
33
30
27
242118 15
12
9
6
3
Ncarbon
end longchains

additional material
C7H7- Tropyl vs. Benzyl
26000
27000
28000
29000
30000
31000
32000
C7D7
from d6-benzene/ Ar
C7H7
from benzene/ Ar
C7H7
from cycloheptatriene/ Ar
26000

27000
28000
29000
30000
31000
-1
32000 cm
7 ring / 6 ring from stable C7H7+ ion!
C7H7- Tropyl vs. Benzyl
C6H5CH2:C
←←X:
tropyl radical
cycloheptatriene / Ar
–complex spectrum
–Jahn-Teller distorted:
–D7h
2 ''
2 ''
E3 ¬ E2
32000
32500
C
toluene / Ar
32000
33000
32500
33000
X
-1
cm
C7H3- identification of the structure!
variety of candidates
calculation :
–energies
–rotational
constants

geometries DFT B3LLYP/6_31G*
C7H3-
rotational K-structure!
close-up of band 1
a.Exp
1
m/z=87 Ion Current (arb.)
6
5
b.Sim
9
4
18890
8
1'
2
18900
18910
7
11
3
12
10
19000

20000
21000
22000
rotational structure!
– down selection: -> 3 member ring
– spin statistics : -> isomer 2
23000
-1
cm
C7H3- structure identified!

no methyl group!
– unlike C9H3 ,C11H3 ,... (Schmidt et al. IJMS 2003)
REMPI aromatics

additional material
Benzene Discharge
C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15
355 nm
C5
R2PI: 278-290 nm
157nm
24
36
48
60
72
84
96
108
120
Mass (amu)
132
144
156
168
180
C8
C9
C10
R2PI: 278-290nm
C11
C12
C13
C14
C10H8
C15
C14H10
F2-Laser: 157nm
96
108
120
132
144
Mass (amu)
156
168
180
R2PI-Spectra from Benzene-Discharge
wavelength / nm
288
287
286
285
284
283
282
281
280
279
0
a
m/z = 102
278
0
0
b
00
m/z = 104
0
291
0
251
281
241
0
0
0
26
271
0
412
1
0
171 181
0
0
0
00
0
m/z = 116
300
260
1
1
1
1
m/z = 178
a(B2u)
34600
34800
35000
A(B1u)
b(B2u)
35200
430 420
1
250
1
S2¬S0: phen
290
280
35400
wavenumber / cm
1
230
1
210
1
B(B1u)
35600
-1
35800
36000
R2PI-Spectra from Benzene-Discharge
wavelength / nm
301 299 297 295 293 291 289
287
285
283
281
279
CH3
m/z = 118
241
00
0
0
291
170
251
0
1
0
422
281 0
191
0
1
1
4
1
1
1
Napht. 70 8
Napht. 40
IP(Napht. )/2
0
Napht. 00
Napht. 80 70 80
0
3
2
1
m/z = 128
m/z = 166
a1
0
0
a1
0
a1
a1
33000
33400
33800
34200
a1 a
1
a1
a1
b2
34600
wavenumber / cm
-1
35000
35400
35800
trans
cis
1
4
2
trans
3
cis
5
end REMPI
Photo Fragmentation Experiment for Cations
1% C 2H2 in Ar
p ~ 10 bar
RETOF as
tandem MS
with double
mass selection !
U
1 2
Cm


AB+ + hn -> A+ + B
, A+ detected
AB+ from source, hn scanned for resonance
Fragmentation spectroscopy


for van der Waals clusters:
M·Arn+ + hn -> M M·Arn-1+ + Ar,
HC4H Arn
M= HC4H
n=4
n=3
n=2
19600
19700
19800
19900
20000
19600
19700
19800
19900
20000
19600
19700
19800
19900
20000
n=1
-1
frequency (cm )
19000
19500
20000
20500
21000
21500
-1
frequency (cm )
22000
22500
23000

extrapolatio
n of band
origins
end Fragmentation

additional material