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Carbon Dioxide Clusters and Copper Complexes Formed in Argon Matrices

Michael E. Goodrich & David T. Moore

Chemistry Department, Lehigh UniversityBethlehem PA, 18015

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Introduction

• CO Oxidation on metal center• Cu(CO)m(O2)n complexes difficult to form

• What happens when both CO and CO2 are in the matrix

• Identify CO2 species in matrix

• Identify Cu(CO)(CO2) clusters

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Experimental• Deposit 0.02-0.5%

CO2 in Argon at 10sccm and 10-20K

• ~4 nA beam of Cu- balanced with a 25-50eV cationic counter ion (Ar+/SF5

+)

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CuCO2 and CO2 Clusters

CuCO2-

CO2-

(CO2-)(CO2)

C2O4-

• 10K Deposition of 0.5% CO2 in Argon with Cu- and Ar+

• Observe conversion of anionic CO2 cluster to oxalate-like C2O4

-

• No apparent conversion to anionic CO2 peaks

Zhou, M.; et al. J. Phys. Chem. A. 103, 2013. (1999) Zhou, M.; Andrews, L. J. Chem. Phys. 110, 2414 (1999)

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CO2 Symmetric Stretch Region

(CO2)2(CO2)2(CO2)2

+CuCO2-

• 10K Deposition of 0.5% CO2 in Argon with Cu- and Ar+

• Minimal changes upon irradiation and annealing

Zhou, M.; et al. J. Phys. Chem. A. 103, 2013. (1999) Castano, J.A.G.; et al. J Mol. Structure 881, 68. (2008).

680 690 700 710 720

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

Abs

orba

nce

Wavenumber (cm-1)

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Effect of Counter Ion Choice on CO2 cluster formation

• SF5+ shuts down the formation of

cationic CO2 clusters• No presence of anionic clusters in

SF5+ spectrum

• High energy argon increases formation of cationic CO2 clusters

SF6

• Anionic clusters present upon deposition of Ar+ suggesting formation is necessary for charge balance

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Matrix Containing CO and CO2

• 0.02% CO & CO2 deposited at 20K

• No presence of CuCO2

-

Cu(CO)2

CuCO-

Cu(CO)2-

Cu(CO)3-

Cu(CO)3 CuCO

C2O3-

• Peaks at 1701 and 1793 cm-1 assigned to C2O3

-

Zhou, M.; Andrews, L. J. Chem Phys. 111, 4548 (1999) Zhou, M.; et al. J. Chem. Phys. 112, 7089 (2000).

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Matrix Containing CO and CO2

• Small CuCO2- peak

when CO2 concentration is higher than CO

• No evidence of ternary Cu(CO)(CO2) complexes

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Conclusions and Future Work

• Identified Copper Carbon Dioxide Clusters and Ionic Carbon Dioxide clusters in an argon matrix

• Can control ionization pathways based on counter ion choice

• Further attempts to form Cu(CO)(CO2) clusters and CuCO2 clusters with CO present in matrix