Robert K. Murawski Homepage

Robert K. Murawski

Assistant Professor of Physics

Physics Department
Drew University
Madison, NJ 07940

Office: Hall of Sciences, Rm. 200: Phone 973-408-3834
rmurawsk@drew.edu

Research Interests:
i)Coherent Anti-Stokes Raman Scattering (CARS) of molecules
ii) Quantum Chemistry and Molecular Dynamics
iii) Dimensional Scaling Analysis in Atomic and Chemical Physics
iv) Non-perturbative energy calculations of strongly correlated systems
v) Quantum Cascade Lasers
vi) Chaos and nonlinear dynamics
vii) Celluar Automatons

i) Coherent Anti-Stokes Raman Scattering (CARS) of molecules

Level diagram of the CARS process. Two femtosecond laser pulses, pump and Stokes, are used to prepare the molecular vibrational coherence. A third pulse, the probe, is scattered off the created coherence resulting in a new forth field, CARS, which is frequency shifted from the probe by ± the vibrational frequency.

Two isomers of dipicolinic acid (DPA) are displayed above. DPA is an important marker molecule for bacterial spores.
The figures were made with VMD.

Spectrogram of a CARS signal produced by Cesium dimers

An interesting spectrogram from Cesium dimers.

ii) Quantum Chemistry and Molecular Dynamics

Shown above is a comparison of the Raman intensities of two isomers of DPA (3,5-DPA above, 2,6-DPA below).
The Raman intensities were calculated with the GAMESS software package.

Here is a movie showing the mixing of water molecules with methanol molecules calculated with GROMACS . Using computer simulations, one can calculate interesting properties of the mixture such as the radial distribution function which is shown here

radial distribution function in methaol water mixtures

CARS maybe a possible method to detect the formation of percolating networks in such binary mixtures.

iii) Dimensional Scaling Analysis in Atomic and Chemical Physics

iv) Non-perturbative energy calculations of strongly correlated systems

v) Quantum Cascade Lasers (QCL)
Title of dissertation:
Optoelectronic properties of Type I InGaAs Quantum Cascade Lasers with Applications to Optical Modulation
Stevens Institute of Technology, May 2004.

Electronic probability density wavefunctions for a QCL

Shown above are the square moduli of the the electronic wavefunctions for a QCL along with the conduction band profile. The functions are offset by the energy level spacing with respect to the potential. The wavefunctions were calculated within the envelope approximation.

vi) Chaos and nonlinear dynamics

vii) Cellular Automatons
In a cellular automaton, a grid of N x M cells is given some initial state. The next iteration of the grid is given by some
rule which depends on the previous state. Shown below is an example of a cellular automaton. Each cell can have a
value between 0 and 63. To update the cells, we can define a rule for Cell_i,j as

Cell_i,j <= (Cell_i,j+ Cell_i-1,j-1 + Cell_i-1,j+1 + Cell_i+1,j-1+ Cell_i+1,j+1) mod 64.

In this example, a grid of a 100 x 100 cells is given the initial conditions that all cells are zero except for a square of
9 cells(in the middle of the grid) which are given the value of C0. After 45 iterations, I get the resulting figures.

c0=1

viii) Miscellaneous images

A section of the Mandelbrot set.

A stereograph of the Mandelbrot set.

A stereogram of the same section of the Mandelbrot set made
with Stereograph for Linux.