ИСТИНА

Photothermal spectroscopy develops in many directions, and since the first analytical paper in 1979 [1] it had been used in various analytical applications, which include highly sensitive photometric measurements and versatile detection schemes in liquid chromatography and capillary electrophoresis. Recently, much attention is paid to the applications of photothermal spectroscopy in microfluidic systems (chemical microchips or µ-TAS), which begin to play a key role in analytical chemistry [2]. However widespread these well-known areas of photothermal applications are, the potentialities of photothermics in analytical chemistry and chemical analysis are even wider. In this lecture, some examples of new relevant analytical applications will be given. As a part of well-known paradigm by Prof. R. Snook that thermal lensing is ‘not just highly sensitive photometry’, the new applications of thermal-lens spectrometry are connected with a recent boom in solid-state spectrophotometry. Novel sensible materials (specially designed polymer matrices or surface-enhanced glasses/films with grafted or absorbed photometric reagents) can be used in the form of transparent chips, films, or resins. These materials serve as transducers in novel gas/aerosol/solute optical sensors and in microfluidics and state-of-the-art separation/preconcentration analytical methods. Photothermal spectroscopy is used for a considerable increase in the sensitivity of photometric measurements of such materials. The examples that will be given include trace metal determination, classical and enzyme kinetic indicator systems for phenolic compounds, immunoassays, and nanoparticle-assisted sensible materials. Moreover, lasers can be used for photoinduced synthesis of nanoparticles in polymer matrices with simultaneous online photothermal control. Another field of application of photothermal spectroscopy is the analysis of heterogeneous materials (solid or liquid), including dynamically appearing and changing heterogeneity. The examples will include the formation of nanoparticles, homogenous formation of crystalline and amorphous residues, the processes of protein crystallization, which can be monitored and analyzed using photothermal techniques. The application of thermal lensing for the quantification, size estimation, and photochemical processes in heme proteins will be discussed. Similar methodological approaches are now used for photothermal detection in biologically active systems like cyanobacteria, diatomic algae and other bacterial pollutants in real water systems or bodies, which can be used for early diagnostics of water pollutions. Finally, the current status of laser, optics and electromechanical technologies provides a sound basis for the development of a plenty of analytical instruments based on photothermal phenomena, and several setups have been made to date. Some schematics under discussion involve differential schemes and those combining several photothermal methods (with laser and non-laser excitation sources), fluorescence, scattering, photoacoustics, etc., relevant for analytical practice (aerosol analysis, table-top analytical instruments, etc.) will be discussed.