Catherine C. Cooksey and Edwin J. Heilweil
Terahertz spectroscopy of biomolecules in aqueous environments is important for identifying global molecular structure and transient environmental interactions. However, water is an extremely strong absorber in the spectral range of 0.5 to 3 THz (15 cm-1 to 100 cm-1). To avoid bulk water absorption, we obtained the terahertz spectrum of the aqueous amino acid, Proline, in the frequency range of 35 cm-1 to 600 cm-1. This spectrum was acquired by solvating the amino acid within the interior water pool of aerosol-OT reverse micelles dispersed in transparent n-heptane. The effect of Proline concentration and reverse micelle size on the terahertz spectrum is reported, and the results are compared to the far-infrared spectra of Proline in bulk water and solid-phase. Results for solvent mixtures are also presented.
Optical Technology Division, Physics Laboratory, Mail Stop 8443
Catherine Cooksey: 216/B105, (301) 975-6208
Edwin Heilweil: 216/B109, (301) 975-2370, Sigma Xi member