The main objectives of our research are the study of molecular structures and quadrupolar coupling parameters. These are obtained through a thorough investigation of each molecule's microwave spectrum. A flowchart describing a typical research project is shown here.
A microwave is just another form of
light, i.e. it is a wave/particle that travels at the speed of light.
The major difference between microwaves and visible light is that microwaves
have much lower frequencies, and hence lower energies.
E = hn
(E is the energy of the light, n
is the frequency and h is just a constant)
Visible light has enough energy to
move electrons around inside molecules, these processes (when reversed)
are what cause materials to glow (fluoresce and phosphoresce). Microwaves
have just enough energy to make molecules spin and rotate like a top.
In your microwave oven you are using microwave radiation to spin around
water molecules, because of friction this action heats up your food.
In our lab we use a spectrometer
that can tune in many frequencies in the microwave region. Then we
put a sample molecule in the chamber and begin looking for the microwave
frequencies that cause it to rotate. If the molecule is rigid like
a wooden top that you might play with, then the frequencies at which it
spins depend only on the placement of masses within the molecule.
By solving the equations which govern rotational motion we can deduce the
structure of the molecule from the information contained in the spectrum.
Full structural analyses of molecules
requires an enormous amount of data, this is directly proportional to the
number of atoms in a given molecule. Whenever we can, we take advantage
of symmetry within the molecule. In the molecule pictured here, there
is a five-fold axis of symmetry. Because
of this the blue (carbon) and yellow (hydrogen) atoms are all in equivalent postitions in the moecule. This limits the amount of data required to determine the structure because once we locate one carbon we have located them all! The same symmetry requirement holds for the hydrogen atoms. In the molecule wherein the purple atom is thallium we have completely determined the molcular structure, and in the case where the purple atom is indium we have determined a limited structure without the hydrogen. For details follow this link, or see the paper published in the Journal of Chemical Physics, Vol. 107 10, p. 3766 (1997).
Many of the pictures of molecules
found on this and linked pages were created with the Moviemol program.
This is a link to Chime images of molecules
in 3D!
Methyl Rhenium Trioxide is a
compound extensively studied in our laboratory and also studied by DFT.
Here is Iron Tetracarbonyl Dihydride
This is my presentation
for Chem 518!
If you have any questions about this
research or about this webpage you can contact me at: