ZAKYA H. FAFAFI

Zakya H. Kafafi - Physical Chemistry

Adjunct Associate Professor. B. S., 1969, University of Houston Ph. D., 1972, Rice University. Assistant Professor of Chemistry. Al-Azhar University, Cairo, Egypt. Visiting Professor/Research Scientist, 1981-1986, Department of Chemistry, Rice University Senior Research Chemist, 1986-present, Naval Research Laboratory, Washington, D. C.

Summary of research interests

I. Spectroscopy and Photochemistry of Molecular Clusters in Condensed Phases. Our research centers on the reactions and photochemistry of metal/semiconductor atoms and small clusters with various classes of organic and inorganic molecules in inert and reactive host matrices. The employed technique of multisurface matrix isolation Fourier transform infrared spectroscopy (MI-FTIR) provides a powerful probe for the following studies:

(1) Microsynthesis and characterization of novel and exotic metal/semiconductor cluster compounds and reaction intermediates.

(2) Delineation of reaction mechanisms of chemical processes on "molecular" metal surfaces.

(3) Identification of vibrational frequencies, molecular symmetry, structure and types of bonding for novel organo- and inorganometallics.

(4) Activation of inert bonds such as C-H, C-C, C-N, N-H, O-H, etc., by broad band and laser photoexcitation. Facilities include a multisurface matrix isolation apparatus interfaced to a Nicolet 740 FTIR spectrometer, argon and krypton ion lasers, a Q-switched Nd:YAG laser, a Nd:YAG/pumped dye laser with a Raman shifter, a CO2 laser line tunable in the 9-11 æm region, two color center lasers tunable from 2.3 to 3.6 æm and an IR WEX laser tunable from 1.5 to 4.5 æm.

II. Novel Nolinear Optical Materials This research focuses on the development and/or characterization of novel mateials for nonlinear optics. Particular emphasis is placed in organics with a metal center such as metal cluster compounds (discrete molecules with one central metal atom, or two or more metal atoms bonded to each other), sandwich compounds, planar/stacked conjugated organometallics, and metal atoms/clusters embedded in polymeric matrices. Recent emphasis has been placed on the three dimensionally p-delocalized all-carbon clusters, Buckminsterfullerene, and its related family. Several synthetic methods are employed using metal atom reactors, high temperature furnaces (up to 2000 oC), vacuum vapor and plasma deposition techniques, and photo-assisted laser vaporization and/or polymerization. Spectroscopic probes (UV, Vis, NIR and IR) are accessible for in vacuo and in situ characterization. Different techniques such as degenerate four wave mixing, second and third harmonic generation and nonlinear spectroscopies are available for studying the nonlinear optical processes in these novel organics and organometallics.

Facilities include a high vacuum film deposition apparatus, a synthetic scale metal atom reactor in addition to various spectroscopic and microscopic techniques used for material characterization. Laser sources dedicated to nonlinear optical characterization include high-powered Q-switched mode-locked Nd:YAG lasers (1064 and 532 nm, 35 ps), synchronously pumped dye lasers (tunable in the visible, 1 ps), and dual Q-switched CO2 lasers (9-11 um, 100 ns).

Selected Publications

"Nonlinear Optical Properties of the Fullerenes C60 and C70 at 1.064 mu." Lindle, J. R.; Pong, R. G. S.; Bartoli, F. J.; Kafafi, Z. H. Phys. Rev. B: Condens. Matter 1993, 48, 9447.

"Reactions of Atomic and Diatomic Iron with Allene in Solid Argon." Ball, D. W.; Pong, R. G. S.; Kafafi, Z. H. J. Am. Chem. Soc. 1993, 115, 2864. "Resonant Nonlinear Optical Response of the Fullerenes C60 and C70." Flom, S. R.; Pong, R. G. S.; Bartoli, F. J.; Kafafi, Z. H. Phys. Rev. B: Condens. Matter 1992, 46, 15598.

"Third-Order Nonlinear Optical Properties of Metallo-Phthalocyanines." Shirk, J. S.; Lindle, J. R.; Bartoli, F. J.; Kafafi, Z. H. Int. J. NLO. Phys. 1992, 1, 699.

"Gold Cluster-Laden Polydiacetylenes: Novel Materials for Nonlinear Optics." Olsen, A. W.; Kafafi, Z. H. J. Am. Chem. Soc. 1991, 113, 7758.