NOVEL CLUSTER STUDIES
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chromium dimer , copper dimer , nickel dimer , silicon dicarbide , cluster reaction chemistry , Mike Geusic , Michael Geusic , M. E. Geusic
Oral Defense by : Michael E. Geusic (Robert A. Welch Predoctoral Fellow) , Rice University
Thesis Title" Cluster Studies within a Supersonic Molecular Beam " April 24, 1985
Committee Members : Dr. Richard E. Smalley , Dr. John L. Margrave , Dr. Frank Tittel (Electrical Engineering )
Abstract
A novel technique for the production of metal and semiconductor clusters based on laser vaporization within the throat of a pulsed supersonic molecular beam nozzle has been developed within our lab. An outline of the overall experimental equipment and detection schemes used for both producing and probing the clusters within the beam will be delineated. A number of studies using this technique have been carried out in an effort to investigate some of the fundamental physical properties such as bonding and reactivities of these species.
The first set of spectroscopic investigations is concerned with the nature of the metal-metal bond in transition metal diatomics. Studies of certain homonuclear transition metal diatomics were conducted using high resolution resonant two-photon ionization spectroscopy in an effort to obtain gas phase data on both the ground state bond lengths and vibrational frequencies of these species. These investigations, as exemplified by chromium dimer, attempted to determine the contribution of the d-orbitals to bonding. Also, data from similar studies on V2, Ni2 and Mo2 is represented in tabular form.
Subsequently, our spectroscopic investigation of the astrophysically important triatomic molecule, silicon dicarbide, is detailed with the ultimate goal of this study being to determine the ground state and excited state bond lengths and geometries of this species. For the past thirty years, the geometry of this molecule was thought to be asymmetric and linear (Si-C-C), however, from the resulting data it is clear that silicon dicarbide is, in actuality, an asymmetric top of C2v symmetry.
The recent development of a reaction tube that when coupled to the aforementioned cluster source has facilitated study of gas phase reaction chemistry on metal clusters (2-30 atoms). Details of this reaction tube and pertinent factors regarding gas conditions contained within the tube during the reaction period will be explained. Initial studies of the variation of reactivity as a function of cluster size have been performed using a select group of reactant molecules (CO, N2, H2 ) and metals. This work has led to interesting results suggesting that a significant variation in reactivity does exist which depends on the metal, cluster size, and reactant.
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**** Certain portions of this thesis have not been included i.e. List of Figures, List of Tables or Appendix etc. ***
TABLE OF CONTENTS
ABSTRACT.. ii
ACKNOWLEDGEMENTS.. iv
LIST OF TABLES.. vi
LIST OF FIGURES..vii
I. INTRODUCTION.. 1
I I I. SPECTROSCOPIC INVESTIGATIONS OF TRANSITION METAL DIATOMICS ( CHROMIUM DIMER ) ..39
IV. SPECTROSCOPIC INVESTIGATION OF SILICON DICARBIDE..65
V. GAS PHASE CLUSTER REACTION STUDIES..94
VI.REFERENCES..162
APPENDIX 1... New Electronic States of Chromium Dimer..170
_____________Personal Comments - Clusters____________
_____________Personal Comments - Fullerenes___________
_________Group Members_between _July 81 - May 85______
Selected Works:
Above-Threshold Ionization With Subpicosecond Laser Pulses
Photodissociation of Carbon Cluster Cations
Superconducting Thin Films Produced by Laser Ablation
Ultrafine Oxide Powders Produced by Rapid Thermal Decomposition
* Supersonic Metal Cluster Beams: Laser Photoionization Studies of Copper Cluster (Cu2) __ Powers, D. E., Hansen, S. G., Geusic, M. E., Puiu, A. C., Hopkins, J. B., Dietz, T. G., Duncan, M. A., Langridge-Smith, P. R. R., Smalley, R. E. __ J. Phys. Chem., 86, 2556, (1982)
* Supersonic Copper Clusters __ D.E. Powers, S.G. Hansen, M.E. Geusic, D.L. Michalopoulos and R.E. Smalley __ J. Chem. Phys.78(6)Part 1, 15 March 1983
*The Bond Length of Cr2 __ D. L. Michalopoulos, M. E. Geusic, S. G. Hansen, D. E. Powers and R. E. Smalley. J. Phys. Chem. 86, 3914-3916 (1982)
* Visible Spectroscopy of Jet-Cooled SiC2: Geometry and Electronic Structure __ D. L. Michalopoulos, M. E. Geusic, P. R. R. Langridge-Smith and R. E. Smalley __ J. Chem. Phys. 80(8) 3556 (15 Apr 1984)
* Hydrogen Chemisorption on Transition Metal Clusters __M.E. Geusic, M.D. Morse and R.E. Smalley __J. Chem. Phys. 82(1) 590 (01 Jan 1985)
* Surface reactions of metal clusters I: The fast flow cluster reactor __ M.E. Geusic , M.D. Morse, S.C. O'Brien and R.E. Smalley __ Rev. Sci. Instrum. 56(11) 2123 (01 Nov 1985)
* Experiments on mass - resolved clusters of semiconductors _ Bloomfield, L. A., M.E. Geusic , R. R. Freeman and W. L. Brown _ Springer Series Opt. Sci. 69:(320), 1985.
* Production and Photofragmentation of Semiconductor Clusters and Cluster Ions _ Bloomfield, L. A., M. E. Geusic , T. J. McIlrath, M. F. Jarrold, R. R. Freeman and W. L. Brown _ In Proceedings of the First NEC Symposium, October 20-23, 1986. Hakone and Kawasaki, Japan.
* Photofragmentation of Mass-Resolved Carbon Cluster Ions: Observation of a "Magic" Neutral Fragment __ M.E. Geusic , T. J. McIlrath, M. F. Jarrold, L. A. Bloomfield , R.R. Freeman and W. L. Brown__ J. Chem. Phys.84(4), 2421 (15 Feb 1986)
* Photodissociation of Carbon Cluster Cations __ Geusic, M. E., M. F. Jarrold, T. J. McIllrath, R. R. Freeman and W. L. Brown __J. Chem. Phys. 86(7)3862 (01 Apr 1987)
* Photofragmentation of Antimony and Bismuth cluster cations at 248 nm __ M.E. Geusic , R.R. Freeman and M.A. Duncan __ J. Chem. Phys.88(1) January 1988
* Neutral and ionic clusters of antimony and bismuth: A comparison of magic numbers __ M. E. Geusic, R. R. Freeman, and M. A. Duncan __ J. Chem. Phys. 89(1) 223 (01 Jul 1988)
*Above-Threshold Ionization With Subpicosecond Laser Pulses_Freeman, R. R., P. H. Bucksbuam, H. Milchberg, S. Darack, D. Schumacher and M. E. Geusic _ Phys. Rev. Lett. 59:(10):1092, 1987
*Preparation and Properties of YBa2Cu3Ox-7 Thin Films on LaAIO3 by Pulsed Laser Ablation _ Geusic, M. E., W. J. Weber and L. R. Pederson _ Materials Letters. 10(1,2):15. Sept. 1990
*Ultrafine Oxide Powders Produced by Rapid Thermal Decomposition of Precursors in Solution _ Matson, D. W., J. C. Linehan and M. E. Geusic _ Particulate Science and Technology. 10:143-154, 1992
Additional information concerning Silicon Dicarbide can be found here
Citations can be found: (portion of original - 1463 / current ~3650) here and here
The original full document can be found here
Dr. Richard E. Smalley, Co-recipient 1996 Noble Prize - June 1943 to October 2005
Questions or Comments: "cluster studies" in the subject line: [email protected]
Note: Some original typing errors have been corrected, although some errors may have been introduced during the input process.