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STOCHASTIC PROCESSES IN SURFACE GROWTH AND IN POLYMER

Pui-Man Lam, Ph.D.
Diola Bagayoko, Ph.D.

 

The study of fluctuations in physical systems is of interest in many disciplines. These disciplines include physics, chemistry, biology, astronomy and mathematics. The stochastic methods used to describe fluctuations have grown enormously in the last few decades and continue to be the subject of very active research. This project aims to apply stochastic methods to the study of processes in surface growth. These processes include deposition, sedimentation, diffusion and epitaxial growth. Such studies can lead to fundamental understanding in thin film growth, which is an important technique in the Fabrication of solid-state devices. Another area of interest is in the application of stochastic methods to study the dynamics of polymer solutions.In this area, Lam and Bagayoko have generalized the influence of uncorrelated white noise on the dynamics of polymer solutions to the case where the correlations depend on both space and time. A noise with space and time dependent correlation is referred to as colored noise. We found that colored noise leads to measurable effects in the dynamic light scattering in polymer solutions.This result sheds light on the dynamics of polymers in solutions. Our studies of stochastic processes have equally been fruitful and led to significant publications in the last two years. This work is supported in part by the Louisiana Education Quality Support Fund (Contract No. LEQSF(1993-94)-ENH-TR-29). It is also supported, through the Timbuktu Academy, by the National Science Foundation (NSF Grant# HRD-9108590) and by the Department of the Navy, Office of Naval Research (ONR Grant# N00014-93-1-1368).

    References:
  1. Dynamic scaling of The island-size distribution and percolation in a model of submonolayer molecular beam epitaxy, J. G. Amar, F. Family and P.M. Lam, Phys. Rev. B50, 8781 (1994).

  2. Ward identities for surface growth models with diffusion, P.M. Lam and D. Bagayoko Phys.Rev. E50, 2488 (1994).

  3. Dynamics of concentration fluctuations in polymer solutions with spatiotemporal correlated noise, P.M. Lam and D. Bagayoko, Phys. Rev. E50, 437 (1994).

  4. Polymer brushes with density dependent excluded volume parameters, P. Anderson, D.C. Hong, P.M. Lam and B.E. Vugmeister, J. Physique II4, 1157(1994).

  5. Spatiotemporal correlations in colored noise, P.M. Lam and D. Bagayoko, Phys. Rev. E48, 3267 (1993).

  6. Renormalization group and simulation studies of groove instabilities in surface growth,l F. Family and P.M. Lam, Physica A205, 272 (1994).

  7. Groove instabilities in surface growth with diffusion, J. G. Amar, P.M. Lam and F. Family, Phys. Rev. E47, 3242 (1993).

  8. Mode-coupling theory and simulation of a running sandpile model of self-organized criticality, P.M. Lam and F. Family, Phys. Rev. E47, 1570 (1993).

 

Selected Publications: Click Here

 

My recent research area is in statistical physics, with application mainly in the area of epitaxial growth and mechanical phenomena of single molecule biopolymers and polymers. I have also done work on theories of phase transitions, percolation and many- body problems. In the last five years I have been supported by the following research funds:

Petroleum Research Fund: P.I. $48,000; June 1, 2004 to August 31, 2007

Board of Regent Support Fund for Research Competitiveness: P.I. $162,000 September 1, 2007 to August 31, 2010

I have published 80 research articles in refereed scientific journals. The following are some of my recent publications.

[1]Driven Translocation of a Polynucleotide Chain Through a Nanopore—A continuous Time Monte-Carlo Study, Pui-Man Lam, Fei Liu and Zhong-can Ou-Yang,  Phys. Rev. E74,011911 (2006)

[2] Unzipping DNA from the condensed globule state—effects of unraveling, P.M. Lam
and J.C. Levy, Biopolymers 79, 287 (2005)

[3] Comment on “Theory of high force DNA stretching and overstretching”, P.M. Lam,  Phys. Rev. E70, 013901 (2004)

[4] Excluded volume effect in unzipping of double stranded DNA, P.M. Lam, J.C. Levy, and H. Huang, Biopolymers, 73, 293 (2004)

[5] Effects of excluded volume in gene stretching, P.M. Lam, Biopolymers 64, 57 (2002)
[6] Monte-Carlo simulation of pulsed laser deposition, P.M. Lam, S.J. Liu and C.H. Woo, Phys. Rev. B66, 45408 (2002)
[7] Monte-Carlo investigation of vertical correlations in self-organized multilayer growth of islands, S. Tan, P.M. Lam and J.C.S. Levy, Physica A303, 105 (2002)
 [8]  A kinetic Monte-Carlo simulation of self-organization in quantum dot superlattices, P.M. Lam and S. Tan, Phys. Rev. B64,35321 (2001)
[9] Extremal-point densities of interface fluctuations in a quenched random medium, P.M. Lam and S. Tan, Phys. Rev. E62, 6246 (2000)
[10] Monte-Carlo simulation of three-dimensional islands, S. Tan and P.-M. Lam, Phys. Rev. B60, 8314 (1999)
[11] Monte-Carlo simulation of coarsening in a model of submonolayer epitaxial growth, P.-M. Lam, D. Bagayoko and X.-Y. Hu, Surf. Sci. 429 161 (1999)
[12] Monte-Carlo investigation island growth in strained layers, S. Tan and P.-M. Lam, Phys. Rev. B59 5871 (1999)

 


 
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