Mohamed Samy El-Shall

Professor
Physical chemistry
(804) 828-3518

Virginia Commonwealth University

Dept. of Chemistry
1001 West Main Street
PO Box 842006
Richmond, VA 23284-2006

804-828-3518(Prof. El-Shall)
804-827-1222(laboratory)
804-828-8599(fax)

Education

B.S., Cairo University
M.S., Cairo University
Ph.D., Georgetown University

Research interests

Our research interests are in the general areas of molecular clusters, gas phase and cluster polymerization, nucleation phenomena and nanostructured materials. The major goal is to gain insights as to how the properties of matter evolve as the size of a material system ranges from molecular to macroscopic dimensions. Research is under way in three areas, each involving a variety of experimental techniques (molecular beams, lasers, mass spectrometry and light scattering) with close collaboration with modern theoretical approaches.

Molecular clusters, gas phase and cluster polymerization

Molecular beam techniques are applied to synthesize different classes of weakly bound molecular clusters and metal atom-doped molecular clusters. Resonant two-photon ionization coupled with time-of-flight mass spectrometry is then applied to study the spectroscopy of size specific clusters. We are interested in measuring the size-dependent spectroscopic lineshifts and lineshapes of a particular atomic or molecular excitation in these clusters.

Read more about the cluster research.

Vapor phase homogeneous and ion-induced nucleation

Nucleation is one of the most ubiquitous and important phenomena in science and technology. It plays a central role in materials science, crystal growth, chemical processing, atmospheric science and cosmochemistry. This research area is of increasing importance to atmospheric chemistry, polar stratospheric clouds, acid rain and air pollution.

Read more about the nucleation work.

Nanostructured materials

Nanoscale particles possess several unique properties such as large surface areas, unusual adsorptive properties, surface defects and fast diffusivities. The intrinsic properties of the interior of the nanocrystals are transformed by quantum size effects. The ability to manipulate the energetics of nanocrystal surfaces at will would have many practical consequences particularly in the fields of catalysis and novel materials.

Read more about the nanoparticle research.

Publications

1. Stepwise Hydration of Ionized Aromatics. Energies, Structures of the Hydrated Benzene Cation, and the Mechanism of Deprotonation Reactions. Y.M. Ibrahim, E.H. Alsharaeh, M. Meot-Ner, S. Scheiner and M.S. El-Shall, J. Am. Chem. Soc. 127, 7053-7064 (2005).

2. Direct Evidence for the Gas Phase Thermal Polymerization of Styrene. Determination of the Initiation Mechanism and Structures of the Early Oligomers by Ion Mobility. E.H. Alsharaeh, Y.M. Ibrahim and M.S. El-Shall, J. Am. Chem. Soc. 127, 6164-6165 (2005).

3. The Chemistry of Styrene (Water)n Clusters, n=1-5: Spectroscopy and Structure of the Neutral Clusters, Deprotonation of Styrene Dimer Cation, and Implication to the Inhibition of Cationic Polymerization. H. Mahmoud, I.N. Germanenko, D. Wright and M.S. El-Shall, J. Phys. Chem. A 109, 4474-4483 (2005).

4. Gas Phase Ion Mobilities and Structures of Benzene Cluster Cations (C6H6)n+, n = 2-6. M. Rusyniak, Y. Ibrahim, D. Wright, S. Khanna and M.S. El-Shall, J. Am. Chem. Soc.125, 12001-12013 (2003).

5. Vapor Phase Growth and Assmbly of Metallic, Intermetallic, Carbon, and Silicon Nanoparticle Filaments. M.S. El-Shall, V. Abdelsayed, Y.B. Pithawalla, E. Alsharach and S.C. Deevi, J. Phys. Chem. B. 107, 2882-2886 (2003) Cover Feature.

6. Mass-Selected Ion Mobility Studies of Isomerization of the Benzene Radical Cation and Binding Energy of the Benzene Dimer Cation. Separation of Isomeric Ions by Dimer Formation. M. Rusyniak, Y. Ibrahim, E. Alsharaeh, M. Meot-Ner and M.S. El-Shall, J. Phys. Chem. A, 107, 7656–7666 (2003).

7. Nanoparticles: Synthesis, Assembly, Properties and Applications. M.S. El-Shall, McGraw-Hill Year book of Science and Technology, 268-272 (2003).

8. Laser Based Synthesis of Intermetallic Cu-Zn Nanoparticles. Y.B. Pithawalla, M.S. El-Shall and S. Deevi, Scripta Materialia, 48, 671-676 (2003).

9. Room Temperature Synthesis and Characterization of Nanocrystalline CdS, ZnS and CdxZn1-xS. W. Wang, I.N. Germanenko and M.S. El-Shall, Chem. Mater. 14, 3028-3033 (2002).

10. Decay Dynamics and Quenching of Photoluminescence from Silicon Nanocrystals by Aromatic Nitro Compounds. I.N. Germanenko, S. Li and M.S. El-Shall, J. Phys. Chem. 105, 59-66 (2001).