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Ab initio and Infrared Studies of Carbon Dioxide Containing Complex

Zheng Su and Yunjie Xu

Department of Chemistry, University of Alberta,

Edmonton, Alberta, Canada

June, 2005

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Introduction Chirality and chiral interaction

Our approaches Ab initio theoretical investigations High resolution molecular spectroscopy

enantiomers

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Molecules under Investigation

Cyclopropane(C3H6)•CO2

CO2 monomer : asym = 2349 cm-1

Accessible region of our laser: 2336 – 2434 cm-1

Propylene Oxide(PO)•CO2

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Ab initio Calculations for PO•CO2 ‡

2.798

2.760

2.711 2.696

2.774

∆ = -2.8 cm-1

∆ E = -18.91 kJ/molA = 3.987 GHz B = 1.635 GHzC = 1.482 GHz

∆ = -3.3 cm-1

∆ E = -18.21 kJ/molA = 5.363 GHzB = 1.261 GHzC = 1.206 GHz

‡ Gaussian 03, MP2/cc-pVDZ for harmonic frequency calculations; MP2/aug-cc-pVDZ for geometry optimizations.

Å

Å

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Simulated Spectrum of PO•CO2

T=2KQ-branch

Kisiel, Z., Białkowska-Jaworska, E. and Pszczółkowski, L., J. Chem. Phys. 109(23), 10263, 1998.

Frequency /cm-1

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Rapid Scan Mid-IR Diode Laser Spectrometer

L5830 TDL control

L5740TDL Dewar

Off-axis parabolic mirror

Beam splitter

iris

Ref. cellor étalon

L3

D2Amplifier 2

Nozzledriver

nozzle

To pump

L1

L2

D1

Amplifier 1Vacuum chamber

cell

Computer Function generator

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Experimental Setup

Laser source dewarCollimation assemblyReference detection

Signal detection of the molecular complex

Vacuum chamber

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Astigmatic Multi-path Cell Assembly

back front

spot pattern of 182-pass configuration → 37m absorption length

Mirror mount

McManus, J.B., Kebabian, P.L. and Zahniser, M.S., Appl. Opt. 34(18), 3336, 1995.

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Rapid Scan Technique

trigger fornozzle driver

current ramp for laser controller

trigger for data acquisition

Piante, A.D., et al., Rev. Sci. Instrum. 60(5), 858, 1989.

Time /ms

background pulse signal

0 1 2 3 4 5

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Example Spectrum of Ar•CO2 R(0)

R0 8

Q0

Randall, R.W., et al., Faraday Discuss. Chem. Soc., 85, 13, 1988.

R(17)R(37)

R(25)

2349.06 2349.42 2349.78 Frequency /cm-1

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Search for PO•CO2 Complex

Carrier gas:

Ar, Ne, He Nozzle:

0.8mm pinhole,

60m slit PO/CO2 ratio:

1/3, 1/1, 2/1, 5/1,10/1

— 0.5% CO2 in 1.5 bar Ar— 0.5% CO2 5% PO in 1.5 bar Ar

2349.24 2349.78 Frequency /cm-1

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∆ E = -28.57 kJ/mol

Vs.

∆ E = -18.91 kJ/mol

Vs.

∆ E = - 7.24 kJ/mol

Competing Formation of Dimers

PO•PO PO•CO2 CO2•CO2

C3H6

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Rovibrational Spectra of C3H6•CO2

2348.82 2349.06 2349.30 Frequency /cm-1

R(16) R(37)R(25)R(32)

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Comparison of Nozzles

C3H6:CO2 = 3:1100 averaging cycles

2347.20 2347.30 2349.40 2349.50 Frequency /cm-1

R(9)R(22)

R(28)

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Simulated Spectra of C3H6•CO2

∆ E = -8.756 kJ/mol∆ = -2.18 cm-1

Frequency /cm-1

∆ E = -9.329 kJ/mol∆ = -5.08 cm-1

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Comparison between Experimental and Simulated Spectra

2344.2 2345.0

2347.84 2348.08 2348.482348.22

Cal.

Exp.

Frequency /cm-1

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Summary and Future Work

Construction of a rapid scan mid-IR diode laser spectrometer

Measurements of C3H6•CO2 complex

Structural analysis of C3H6•CO2 complex

Investigation of PO•CO2 complex Study of chiral interactions

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Acknowledgement

Dr. Waishun Tam and Dr. Nicole Borho Dr. Wolfgang Jäger and his group Dr. Igor Leonov for programming Roman Lipiecki for the mechanical parts Alberta Ingenuity Fund for a Studentship NSERC Thank you for the attention !!!