Optical methods in condensed matter studies

Participating countries and international organizations:

Armenia, Belarus, Cuba, Egypt, India, Kazakhstan, Russia, Serbia, Uzbekistan, Vietnam.

The problem under study and the main purpose of the research: 

Fundamental and applied studies of low-dimensional materials (2D materials and van der Waals heterostructures) using Raman spectroscopy and upconversion luminescence. Fluorescence microscopy and vibrational spectroscopy in studies of photo-activated programmed cell death (netosis and apaptosis). Spectroscopy of lipid-protein interactions and secondary structure of proteins. Mastering low-frequency Raman spectroscopy.

Brief annotation and scientific rationale:

Since the exfoliation of graphene in 2004, two-dimensional materials (2DMs) have attracted much attention due to the qualitative changes in their physical and chemical properties due to quantum size effect associated with their nanoscale thicknesses. Atomically thin two-dimensional transition metal dichalcogenides (TMDCs), such as MoS₂, WSe₂, and others, exhibit strong light-matter coupling, making them potentially interesting candidates for various applications in electronics, optics, and optoelectronics. They can be assembled to form heterostructures and combine the unique properties of their constituent monolayers. Raman spectroscopy is one of the most non-destructive and relatively fast technique for characterizing such materials, providing high spectral resolution. Vibrational frequencies in the Raman spectrum of low-dimensional materials exhibit characteristic features of the sample, including line shape, peak position, spectral width, and intensity. These parameters provide useful information about the physical, chemical, electronic, and transport properties of such materials.

Optical research methods are also very promising in Life Sciences. In particular, combining vibrational spectroscopy with fluorescence microscopy will allow a detailed study of the mechanisms and signalling pathways of photo-activated programmed cell death– NETosis. Raman spectroscopy is also a subtle tool in revealing the secondary structure of proteins and is sensitive to lipid-protein interactions.

Expected results upon completion of the project:

1. Measurement and characterization of the transport properties of 2DMs and vdWHs depending on the excitation photon energy.

2. Mechanism of Raman enhancement effects from analyte molecules adsorbed on two-dimensional materials. Study of their protective properties applied to biomolecules.

3. Up-conversion luminescence on a low-dimensional platform: studies depending on the sample, temperature and excitation wavelength.

4. Spectroscopic analysis of conformational transformations in the secondary structure of proteins present in various membrane mimetics, including, temperature, pH, and additives dependance.

5. Simulation of lipid-protein interaction by MD and DFT.

6. Identification of the mechanisms and signaling pathways of photoinduced NETosis by UV, visible and IR radiation. Identification of primary acceptors of photo-induced NETosis.

7. Characterization of the effects of simultaneous and sequential exposure to laser radiation on intact neutrophil cells at two different wavelengths.

8. Raman spectroscopy of ultra-low frequencies ~ 10 cm^-1 at different wavelengths of excitation of the Raman signal. 

Expected results of the project in the current year:

1. Measurements and analysis of Raman spectra of graphene, molybdenum disulfide, and van der Waals heterostructures based on them.

2. Initiation of studies of transport properties of low-dimensional materials depending on the laser excitation photon energy.

3. Detailing of protein secondary structure in membrane mimetics by Raman spectroscopy; modeling by methods of molecular dynamics and density functional theory.

4. Identification of primary photoacceptors of photoinduced netosis NETosis.