Improved detection sensitivity of D-mannitol crystalline phase content using differential spectral phase shift terahertz spectroscopy measurements.

Jean-François Allard, Alain Cornet, Christophe Debacq, Marc Meurens, Daniel Houde, Denis Morris

Département de radiobiologie et médecine nucléaire, Université de Sherbrooke, Sherbrooke, Québec, Canada.

Optics express 2011 Feb 28

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We report quantitative measurement of the relative proportion of δ- and β-D-mannitol crystalline phases inserted into polyethylene powder pellets, obtained by time-domain terahertz spectroscopy. Nine absorption bands have been identified from 0.2 THz to 2.2 THz. The best quantification of the δ-phase proportion is made using the 1.01 THz absorption band. Coherent detection allows using the spectral phase shift of the transmitted THz waveform to improve the detection sensitivity of the relative δ-phase proportion. We argue that differential phase shift measurements are less sensitive to samples' defects. Using a linear phase shift compensation for pellets of slightly different thicknesses, we were able to distinguish a 0.5% variation in δ-phase proportion.

Citation

Jean-François Allard, Alain Cornet, Christophe Debacq, Marc Meurens, Daniel Houde, Denis Morris. Improved detection sensitivity of D-mannitol crystalline phase content using differential spectral phase shift terahertz spectroscopy measurements. Optics express. 2011 Feb 28;19(5):4644-52