Infrared spectrum
of
the (CO2)2-N2O trimer measured
in N2O n1 and n3 regions
J. Norooz Oliaee, N. Moazzen-Ahmadi
Department of Physics and Astronomy, University of Calgary, Canada
and
A. R. W. McKellar
National Research Council of Canada
Infrared spectrum of two trimers:
(CO2)2-N2O and CO2-(N2O)2
measured in N2O n1 and n3 regions
J. Norooz Oliaee, N. Moazzen-Ahmadi
Department of Physics and Astronomy, University of Calgary, Canada
and
A. R. W. McKellar
National Research Council of Canada
Experimental setup:
Pulsed supersonic jet apparatus with a tunable diode laser probe
Jet Controller (Iota One)
Jet
Trigger
Jet Controller
TDL Controller (L5830)
Gas Supply
TDL
IR Detectors
Jet Signal
Laser
Sweep/
Trigger
Timer Controller
DAQ
Trigger
Card (CTR05)
Monochromator
Ref. Gas
12 bit
DAQ Card
Etalon
N2O-CO2: The first study in infrared region
Two possible slipped-parallel configurations
HF/6-311g* energy minima for five planar geometries of CO2-N2O
N2O-CO2: Subsequent Microwave Studies


N2O-CO2: More recent infrared study
5 infrared bands observed (band origins in cm-1):
3 fundamentals
CO2 n3
N2O n1
N2O n3
2348.8646(1)
2225.7532(1)
1279.5847(4)
2 combinations
CO2 n3 + torsion
N2O n1 + torsion
2374.6666(1)
2251.4597(1)
wtorsion ≈ 25.8 cm-1
N2O-CO2: Very recent theoretical study
34.17
MK07
A trimer of N2O and CO2: (CO2)2-N2O
• 7 isotopologues studied: barrel-like structure
• C1 symmetry
• Each CO2-N2O pair resembles the dimer
• Semi-empirical calculation with Orient
program
(CO2)2-N2O: First infrared spectrum
2226.950 cm-1
2225.753 cm-1
(CO2)2-N2O: First infrared spectrum
(CO2)2-N2O: molecular parameters
Ground State *
Excited State
n0 / cm-1
-
2226.949865(58)
A / MHz
1597.4578(29)
1593.27(91)
B / MHz
1232.9688(16)
1232.30(38)
C / MHz
831.0955(11)
830.460(58)
DJ / kHz
2.610(33)
12.9(3.1)
DJK / kHz
-3.63(14)
-51(17)
DK / kHz
7.30(36)
7.30†
dJ / kHz
0.830(16)
5.8(1.5)
dK / kHz
0.72(10)
4.3(2.8)
* Ground state parameters are fixed at the values from Peebles et al., Mol. Phys. 96, 1355 (1999).
† Fixed at ground state value.
Dn / cm-1
N2O-CO2
N2O-(CO2)2
+1.99
+3.19
Another trimer of N2O and CO2: (N2O)2-CO2
• N2O n3 region ≈1285 cm-1
• Cluster calculations: C2 structure
1275.55 cm-1
×
Another trimer of N2O and CO2: (N2O)2-CO2
b
⊙
a
c
a/c-type
resolution
≈ 55 MHz
Trot ≈ 2.4 K
(N2O)2-CO2 : rotational constants
Observed
Calculation
Obs.-Cal.
A / MHz
1612.52(84)
1641.73
-29.21
B / MHz
1289.37(73)
1308.79
-19.42
C / MHz
864.68(52)
881.34
-16.66
Similar structure to: (C2 symmetry)
Energy
-1642 cm-1
Summary
• Infrared spectrum of (CO2)2-N2O is observed in N2O n1 region (≈ 2224 cm-1)
• A new trimer, (N2O)2-CO2 , is observed in N2O n3 region (≈ 1285 cm-1)
Future directions:
• Isotopic substitution studies on (N2O)2-CO2
• Re-measure band of (N2O)2-CO2 in N2O n3 region (≈ 1285 cm-1)
• Search for corresponding band of (N2O)2-CO2 in N2O n1 region (≈ 2224 cm-1)
Acknowledgements
• A. R. W. McKellar
Nasser Moazzen-Ahmadi •
THANK YOU