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33THz-O-6
Study of the spectrum of bound water in 0.07-2.6 THz range
M. Konnikova1, M. Nazarov2, O. Cherkasova3,4, A. Shkurinov1,5
1M. V.Lomonosov Moscow State University, Department of Physics and International Laser Center, Moscow, Russian Federation
2Kurchatov Institute National Research Center, Photonics and additive technologies, Moscow, Russian Federation
3Institute of Laser Physics of SB RAS, Biophysics Laboratory, Novosibirsk, Russian Federation 4Tomsk State University, laboratory of Biophotonics, Tomsk, Russian Federation 5FSRC «Crystallography and Photonics» RAS, Crystallography and Photonics, Shatura, Russian Federation
Water plays a huge role in the functioning of biological systems and can be classified as a bulk and bound water [1]. Strongly or weakly bound water, as well as free (unbound) water, makes valuable but different contribution to the THz response of biological objects. The reason for the change in the THz response in biological samples is the transition of part of water from free to bound state and back. To interpret the results, we need to know precisely spectrum of bound water. Our measurements were performed using two THz-TDS spectrometers described previously [2, 3]. We measured the THz spectra of dry and wet glucose pressed into tablets. Then we added some water to these tablets and again measured the THz spectra. Water concentrations in glucose were varied from 0% to 30% (v/v). THz signal of free water starts to appear after 14-16% v/v water concentrations in glucose. Till 30% water concentrations glucose, free water and crystals coexists in this mixture, even phonon resonances are detectable. In THz absorption spectra we can recognize the contribution both free water (by strong dispersion below 0.2 THz) as well as glucose crystals with its own phonon spectra above 1.4 THz. We obtained the absorption of bound water and confirmed that it is an order of magnitude less than that of free water. This study was funded by RFBR projects №» 17-00-00275 (17-00-00270) and 18-52-00040 (in data processing part), by the Ministry of Science within the State assignment FSRC «Crystallography and Photonics» RAS in part of equipment.
References
[1] O.A. Smolyanskaya et al., Progress in Quantum Electronics vol. 62, pp. 1-77, 2018.
[2] M.M. Nazarov et al., Quantum Electronics, vol. 46(6), pp. 488-495, 2016.
[3] M.M. Nazarov et al, J Infrared Mill.Terah.Waves, vol. 39, pp. 840-853, 2018.
