Date of Award
Master of Science (MS)
Harold K. Haugen
This thesis details the development of a multi-functional THz system capable
of operating in three different geometrical configurations: transmission, reflection
and attenuated total reflection (ATR). This apparatus can be used to collect THz
time-domain spectroscopic data or it can be used to study the carrier dynamics of a
system following optical excitation. These two functions categorize the two types of
experiments presented in this thesis.
THz time-domain spectroscopy (TDS) was performed with the transmission and
reflection configurations to determine the feasibility of using THz radiation to study
thin polymer films. This technique was also performed in an ATR configuration
with the use of a high purity Si prism. The THz ATR method was developed to
extend the capabilities of the system to accommodate liquid samples. '!\fater was the
primary sample of interest, however methanol, ethanol and sucrose solutions were
also examined. Although the results obtained regarding water are inconsistent with
the literature, it has led to valuable insight as to ho\', the current experimental setup
may be improved.
The optical-pump THz-probe technique was also incorporated \\ ith each of the
configurations of the system. In transmission mode, the carrier dynamics of ZnSe
nanowires were studied. In reflection mode, the optical-pump, THz-probe capabilities
were tested using a Si wafer sample. In the ATR configuration, the carrier dynamics
of the Si prism itself were examined. It is necessary to characterize the response of
the prism to optical excitation if this technique is to be applied to samples placed
on the surface of the prism. Efforts were made to control the free carrier lifetime of
the near surface region of the Si prism, by irradiating the surface of the prism with
a high energy proton beam to create defects in the Si. The results from this initial
experiment, along with suggestions for future follow-up experiments, are presented.
Armstrong, Clare, "DEVELOPMENT OF AN APPARATUS FOR ULTRAFAST THz SPECTROSCOPY" (2009). Open Access Dissertations and Theses. Paper 4067.
McMaster University Library