The transmission spectra of the most common hyperosmotic agents, such as pure glycerol, propylene glycol (PG), dimethyl sulfoxide (DMSO), polyethylene glycol (PEG) with 200, 300, 400 and 600 Da molecular weights, and their aqueous solutions, as well as aqueous solutions of sucrose, glucose, fructose, dextran 40 and 70 were measured. The experiments were carried out using a THz pulsed spectrometer with a vacuum measuring compartment to reduce the effect of water vapor on spectral measurements. The dielectric properties of hyperosmotic agents were restored in the spectral range from 0.1 to 2.5 THz and the dependence of the amplitude absorption coefficient on the concentration of considered agents at 0.5 THz frequency was constructed. The obtained results make it possible to choose the optimal agents for immersion optical clearing in the THz range.

Using methods of infrared, terahertz, and submillimeter spectroscopy, experimental transmission and reflection spectra of α-lactose monohydrate have been obtained at room temperature in the frequency range from 5 to 5000 cm^–1. The experimental spectra of dense pressed tablets and powdered samples have been analyzed in terms of the model of a classical oscillator. Certain parameters of absorption bands of the resonant and quasi-relaxation types are markers by which components can be selected in heterogeneous pharmacological and organic preparations using the methods of coherent submillimeter and pulsed terahertz spectroscopy.

The reflection spectra of pure single-phase pressed samples of saccharides were measured using coherent submillimeter, pulsed terahertz, and broadband Fourier IR spectroscopy, and the parameters of their absorption bands were estimated using an additive classical oscillator model. The possibility of analyzing the vibrational spectrum with the correction of scattering from calibration data in the visible and terahertz ranges is shown. The sensitivity and accuracy of this approach are limited by the low values of reflection coefficient and, as a consequence, the low signal-to-noise ratio, as well as the asymmetric broadening of the bands associated with the anharmonicity of the vibrations and the overlap of the absorption lines.