Time domain terahertz spectroscopy: construction of the setup and application in analysis of active pharmaceutical ingredients

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2016

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Aytekin, Yusuf Samet

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The purpose of this thesis is to build a homemade Terahertz (THz) Time Domain Spectrometer and analysis of Active Pharmaceutical Ingredients (API) by using the built THz-TDS spectrometer. Several configurations of THz-TDS system were setup and tested in order to optimise experimental parameters. These set-ups can be grouped into two; antenna-antenna and antenna-crystal. In antenna-antenna systems, photoconductive antenna (PCA)and interdigital photoconductive antenna (iPCA) were employed and both were tried for generation and detection of THz field. None of the two set-ups resulted in a good signal-to-noise ratio (SNR) or dynamical range (DR) both in time domain and frequency domain. In antenna-crystal systems, both PCA and iPCA were employed for terahertz generation and 500 µm ZnTe crystal was used for electro-optic sampling. In this case, iPCA-crystal combination gave the best SNR and larger dynamical range. Once the generation and detection types were determined, optimisation studies were carried out to measure optical properties of APIs. A modelocked oscillator Ti:Sapphire laser with central wavelength of 800 nm, repetition rate of 80 MHz, pulse duration of 80 fs and output power of ~550 mW was used as the laser source to generate and detect THz radiation. The final system has 3 THz bandwitdh and > 105 SNR. Afterwards, several APIs of common drugs were analysed by using both the optimised homemade THz-TDS setup and FT-THz system. The results have shown that each API had a characteristic THz spectrum, that can be used for the identification and characterisation of API.

Subject Keywords

Drugs, Terahertz spectroscopy.

URI

http://etd.lib.metu.edu.tr/upload/12620303/index.pdf
https://hdl.handle.net/11511/25846

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

Y. S. Aytekin, “Time domain terahertz spectroscopy: construction of the setup and application in analysis of active pharmaceutical ingredients,” M.S. - Master of Science, Middle East Technical University, 2016.