Mid-Infrared Tunable Lasers
Figure 5. (left) This graph shows methane spectra calculated from a Hitran database. The arrow indicates the 13C peak used for measurements. (right) This chart
illustrates the photoacoustic spectra of laboratory air. Courtesy of Radboud University.
At the École Polytechnique Fédérale de
Lausanne (EPFL) in Switzerland, professor Rainer Beck and his research group
are studying chemical reactions between
gas molecules and solid surfaces.
Processes in surface chemistry such as
heterogeneous catalysis and chemical
vapor deposition are important in many industrial implementations, such as catalytic
conversion in automobiles and semiconductor growth in the electronics industry.
In Beck’s laboratory, researchers are
studying the effects of laser excitation in
such processes. The results of these experiments provide stringent tests for theoretical models of gas-surface chemistry.
The group is currently using an Acu-
light Argos CW OPO to study the reaction
of methane with a nickel catalyst. The
OPO prepares a beam of methane molecules in a specific excited state. To preserve the molecules in this state, the
preparation is performed under collision-free conditions in a molecular beam (
Figure 4), whereby the absorption feature is
reduced to less than a few megahertz in
width. The high spectral resolution and