Fourier Transform Spectroscopy of Rare Earth Elements

Dave Nitz

My research interests are in atomic physics, which uses a variety of experimental techniques to learn about the fundamental properties of free atoms and how they interact with each other.  Recent projects have been in emission spectroscopy, whose basic concept is to create excited-state atoms in an electrical discharge and analyze the light they emit as they decay to states of lower energy.

The problem I have been studying can be summarized as follows: given an atom in a particular excited state, to which of its lower states will it decay and what is the probability for each of the different decay channels?  The strategy for doing this is to record an emission spectrum for the atom of interest (we use a technique called Fourier Transform Spectroscopy) and use an interactive computer program to systematically search for and measure the strength of signals whose photon energies correspond to known energy level differences in the atom.  The information obtained contributes to our fundamental understanding of atomic structure, and it is also of practical interest to scientists in other fields who use emission spectroscopy as a diagnostic tool (e.g., for studying a complicated environment like the atmosphere of a star, or for trying to figure out what trace elements to add to a fluorescent light to improve its color rendition and efficiency).

In collaboration with scientists at the University of Wisconsin and at NIST (National Institute of Standards and Technology), we have been working to increase significantly the number of fully-characterized decay branches of rare earth elements like cerium, which have thousands of observable spectral lines.