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.

With a change in temperature, a-lactose monohydrate crystals undergo changes in the molecular structure due to dehydration and decay of intramolecular bonds. The transmission spectra of the pressed microcrystalline samples of a-lactose monohydrate were measured using terahertz pulsed spectroscopy in the temperature range of the existence of the solid phase 10 – 475 K. An analysis of the observed absorption lines using the classical oscillator model made it possible to reveal the complex temperature evolution of the eigenfreuencies of the resonances, as well as to determine the region of existence of response phase of a-lactose monohydrate. Data obtained can find practical application in various fields of terahertz optics, including pharmacology, food industry, analytical chemistry and biophotonics.

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.