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Infrared Spectroscopy of Gas Phase Protonated CO 2 Clusters. Gary E. Douberly , Allen M. Ricks, Brian W. Ticknor, and Michael A. Duncan Department of Chemsitry University of Georgia http://www.arches.uga.edu/~maduncan. Funding: National Science Foundation. Motivation. - PowerPoint PPT Presentation
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Infrared Spectroscopy of Gas Phase Protonated CO2 Clusters
Gary E. Douberly, Allen M. Ricks, Brian W. Ticknor, and Michael A. Duncan
Department of ChemsitryDepartment of Chemsitry
University of GeorgiaUniversity of Georgiahttp://www.arches.uga.edu/~maduncan
Funding: National Science Foundation
Motivation
• Implementation of pulsed electric discharge source for protonated molecular clusters
• Infrared Spectroscopy of Mass-Selected Clusters
• Insight into proton environment with increasing cluster size. Structural Information
Experiment
Pulsed Discharge Cluster Source
0 250 500 750 1000 1250 1500 1750 2000 2250 2500
n=56
n=16
m/z
n=4H+(CO
2)n
300 psi1:10:100CO2 : H2 : (70/30) Ne/He
88 132 176 220 264 308 352 396 440
264 272 280 288 296 304 312 320 328
m/z
m/z
(n,m)
(1,6)
(2,5)
(3,4)
(4,3)
(5,2)
(6,1)
H+(CO2)n - Ar
m
(7,0)
300 psi1:10:20:100CO2 : H2 : Ar : (70/30) Ne/He
n=2
n=3
OPO OPA
1 crystalangle tuned
4 crystalsangle tuned
signal (not used)
idler
532 nm
1064 nm
KTPoscillator
KTAdiff. gen.
+ amp of idler beam
LiInS2
diff. gen.
Tunable4.2-10.1 m
2 crystalsangle tuned
Tunable mid-IR2.3-5.0 m
900 V
750 ns
LaserVision (Dean Guyer)
0 50 100 150 200 250 300 350
m/z
H+(CO
2)7
OPO On - Off
(cm-1) e ee D0
1 242.8 11.8 1130
2 182.4 3.6 2210
1800 2100 2400 2700 3000 3300 3600
Wavenumber (cm-1)
2+n
s
CO2H+
Ar-CO2H+
1+n
s
MP2 / aug-cc-pVTZ
s = 184.3 cm-1
D0 = 2400 cm-1
Protonated CO2 Dopfer O, …, Maier J; Chem Phys Lett. (1998) 296, 585.
1800 2100 2400 2700 3000 3300 3600
Wavenumber (cm-1)
Protonated CO2 Dimer
Monomer proton stretch
1000 1250 1500 1750 2000 2250 2500 2750 3000
Wavenumber (cm-1)
H+(CO2)
2-Ar
e = 153 cm-1 D
0 = 640 cm-1
MP2 / 6-311++G(2d,2p)
s = 127 cm-1
De = 660 cm-1
Protonated CO2 Dimer
(cm-1) H+(CO2)3 H+(CO2)3-ArDe Local 2630 790 De Global 3080 960
1000 1250 1500 1750 2000 2250 2500
Wavenumber (cm-1)
H+(CO2)3-Ar
loss of Ar
Protonated CO2 Trimer
Protonated CO2 Tetramer
1000 1250 1500 1750 2000 2250 2500
H+(CO2)3-Ar
loss of Ar
Wavenumber (cm-1)
H+(CO2)4-Ar
loss of Ar
Microsolvationof n=3 motif
44 88 132 176 220 264 308 352 396
2300 2350 2400 2450
0
1
2
3
4
5
6
7
8
Wavenumber (cm-1)
m/z
H+(CO2)7
Mode specific fragmentationdynamics
Summary
• Demonstration of pulsed electric discharge cluster source for argon tagged H+(CO2)n
• IR spectra from 950 to 2600 cm-1 reveals a rearrangement of Dimer structural motif for n=3
• Other protonated molecular clusters studied:
H+(CO)n , H+(H2O)n , H+(C3H6O)n , H+(O2)n , H+(N2)n
H+(C2H2)n , H+(C2H4)n, H3+(Ar)n, etc.
RF06
Protonated Acetylene and Ethylene Clusters
900 1200 1500 1800 2100 2400 2700 3000 3300 3600 3900
Wavenumber (cm-1)
Protonated Acetone Monomer and Dimer
Loss of Ar
eg.
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