Terahertz radiation refers to a specific part of the electromagnetic spectrum, flanked by microwave and infrared radiation at the higher and lower frequency end respectively. This thesis is about the development of applications using a new source of pulsed, coherent light for the physical characterisation of solids in the pharmaceutical setting.
Terahertz radiation has excellent potential in the advancement of science but is, as yet, largely unexplored. Recent developments in semiconductor physics have made it possible to provide light at terahertz frequencies (a frequency of 1 THz equals a wavelength of 0.3 mm) in a relatively easy way. Light located in this range of the electromagnetic spectrum was very difficult to generate previously. It has unique properties in that it is possible to extract the full spectroscopic fingerprint of the materials by looking at the frequency response of the terahertz pulse. Here, vibrations of the whole molecule are probed rather than just the vibrations of single functional moieties within a molecules as is the case in infrared spectroscopy, which makes terahertz spectroscopy a very powerful tool for the analysis of the complex solid-state materials properties.
In addition to structural information it easily penetrates through most plastics and polymeric materials used as excipients for pharmaceutical tablets. It is therefore especially useful for non-destructive imaging applications.
At the example of polymorphic phase transitions, dehydration processes and crystallization experiments from the amorphous phase the potential of terahertz spectroscopy for pharmaceutical analysis was systematically investigated. In addition, a novel concept for using terahertz radiation in structural imaging of pharmaceutical dosage forms was developed.
The technology, thus far predominantly used for the analysis of inorganic materials and semiconductors in particular, is now mature enough for its application to a wider field and to help with the understanding of fundamental and exciting new challenges at the interface between physics and the life sciences.
Together with a comparison of this new technology to the established techniques in physical characterisation an initial attempt to understand and interpret the spectral information provided is presented. The potential for future applications is discussed.
| Identifer | oai:union.ndltd.org:ADTP/217723 |
| Date | January 2007 |
| Creators | Zeitler, J. Axel, n/a |
| Publisher | University of Otago. School of Pharmacy |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://policy01.otago.ac.nz/policies/FMPro?-db=policies.fm&-format=viewpolicy.html&-lay=viewpolicy&-sortfield=Title&Type=Academic&-recid=33025&-find), Copyright J. Axel Zeitler |
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