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Department of Physics, Applied Physics, and Astronomy
Rensselaer Polytechnic Institute
110 Eighth Street, Troy, New York 12180-3590 USA

Telephone:
(518) 276-6310
Fax: (518) 276-6680
E-mail: physics@rpi.edu

John Schroeder
John Schroeder

Professor of Physics

Contact:
(518) 276-8408
schroj@rpi.edu

Education:
Ph.D., Physics, The Catholic University of America, Washington, D.C.
B.S., M.S., University of Rochester.

Career Highlights:
Prior to joining the faculty of Rensselaer in January, 1982, he was a commissioned officer in the U.S. Navy from June, 1962, to January, 1970. From 1975 to 1978 Professor Schroeder was a Post-Doctoral Associate in the School of Chemical Sciences and a Senior staff member of the Materials Research Laboratory at the University of Illinois in Champaign/Urbana. In l978, he joined the General Electric Corporate Research and Development Center in Schenectady, NY. He did basic glass and ceramic material research and examined material behavior at ultra high pressure (diamonds).

At Rensselaer he studied the optical and magnetic properties of glasses using Rayleigh, Brillouin and Raman spectroscopic techniques at extremes of pressure and temperatures.

Recently Schroeder has worked on confirming the existence of intermediate range order in glasses leading to an explanation of the existence of non-exponential structural relaxation in glasses. He also leads a program of optical characterization of nanocrystalline (II-VI and IV) semiconductors with high pressure being a most important parameter. Now, he also works on the problem of cataract formation in the human lens employing photoluminescence spectroscopy and perturbative colorimetry techniques.

Schroeder is the author or coauthor of over 110 published technical articles in refereed journals and proceedings. Under Schroeder’s guidance ten Ph.D. thesis students and eight M.S. students have completed their degrees. He has also supervised undergraduate research participants for over twenty students.

Research Interests:
Glass Physics
A pressing problem of fundamental nature is the concept of intermediate range order in glass. The existence of non-exponential structural relaxation in glasses can only be reconciled if intermediate range order or "nanoscale" inhomogeneities exist in glasses. Schroeder’s work addresses this crucial question of the existence of intermediate range order in glasses by the Boson peak measurements with Raman spectroscopy and the anomalous Rayleigh scattering detected near the glass transition region of all glasses. Here pressure, temperature and composition are the major variables employed in the studies.

Nanoparticle Physics
Solids that have typical sizes in the mesoscopic range (nanometer dimensions) exhibit optical properties and magnetic properties that differ remarkable from bulk crystals of the same composition. The phase stability may change or be enhanced by the smallness of the semiconductor particles. Schroeder and students have addressed many of the above issues. Their measurements in terms of photoluminescence and Raman scattering at high pressures were the first to show enhanced phase stability of II-VI nanoparticles in glass composites and colloids. Their electron-phonon coupling studies of II-VI nanocrystal composites as a function of pressure were the first impetus to theorists to reconsider this unsolved problem. Professor Schroeder and co-workers are also investigating magnetooptic effects in nanocrystalline composites to obtain a suitable base material for very sensitive magnetometer devices.

Cataract Studies in Human Lenses
Schroeder and Kandel (Cognitive Sciences - Psychology) have carried out a series of studies on in-vitro human lenses and developed a model for cataract formation and its age dependence. They developed a device based on perturbative colorimetry to study the aging process of the human lens non-invasively. This work continues with emphasis on understanding methods to slow down the rate of cataractogenesis.

Selected Publications:
M..R. Silvestri and J. Schroeder. “Pressure and Laser Tuned Raman Scattering In II-IV Semiconductor Nanocrystals: Electron-Phonon Coupling” Phys. Rev B50, 15108 (1994).

J. Schroeder and P.D. Persans. “Spectroscopy of II-VI Nanocrystals at High Pressure and HighTemperture.” J. of Luminescence 70, 69 (1996).

D.B. Hall, K.A. Vogel, and J. Schroeder. “Magnetic Susceptibility and Farady Rotation in Zirconium Based Fluoride Glasses.” J. of Physics: Condensed Matter 10(26), 6009 (1998).

M. Lee, S.K. Saha, C.T. Moynihan, and J. Schroeder. “Non-exponential Structural Relaxation, Anomalous Light Scattering and Nanoscale Inhomogeneities in Glasses.” J. Non-Cryst. Solids 231, 369 (1997).

Y.T. Lee, J. Schroeder, C.S. Choi and J. Frankel. “Vibrational Relaxation and Molecular Reorientation in Aqueous Solutions of Ammonium Nitrate Salts.” Molec. Phys. (2000) in press.

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