E.M. Filippova

Saturation spectroscopy as a method for determining the photophysical parameters of complicated organic compounds

A fundamentally new approach to the fluorescence diagnostics of complicated organic compounds and complexes has been proposed. The method is based on in vivo and in situ measurements of the photophysical parameters of organic molecules from saturation curves. The results obtained for the solution of the relevant inverse problem are presented.

New possibilities of laser fluorescence spectroscopy for diagnostics of petroleum hydrocarbons in natural water

New possibilities of fluorescence spectroscopy for diagnostics of oil pollution in natural water are discussed. It is shown that the choice of shorter excitation wavelengths than is accepted in the standard UNESCO technique for the determination of petroleum hydrocarbons concentration significantly improves the sensitivity and universality of the method and allows one to perform oil classification into basic classes. The authors have also considered the principal possibilities of direct (without extraction) fluorescence diagnostics under excitation at 266 nm. The results obtained may be considered as the next step to solve the very difficult problems of laser remote sensing of oil pollution in natural waters.<<ETX>>

Origin and structure of fluorescence band from aquatic humic substances

The different spectral-luminescence characteristics of humic substances were investigated. Hypothesis for the origin and the structure of fluorescence band from humic matter are discussed.

Laser remote sensing of dissolved organic matter in natural water

Fluorescent methods using Raman scattering signal as an internal standard are widely applied for environment remote control of dissolved organic matter (DOM) in water. In this paper temperature variations, ultraviolet irradiation influence on exitation and emission spectra of water samples have been investigated. Photochemical processes in DOM under laser excitation and the effect of fluorescence saturation have been studied.<<ETX>>

Fluorescence spectroscopy as a method for in-situ measurements of water quality

The paper summaries the results of laboratory and field experiments during August 1991, September 1997 and 1998 along the Russian coast of the Black Sea. The main objects of investigation were aquatic humic substances, dissolved protein-like molecules (free and combined amino acids) and petroleum hydrocarbons in dissolved-emulsified state in the water column. Spectral luminescence characteristics of various water samples were investigated using laser spectrometers with excitation wavelengths 266 and 337 nm and lamp fluorescence spectrometers. Relying on these results we briefly review the opportunity of the method when the wavelength of exciting radiation is located in the range of 310...400 nm. We also discuss advantages of fluorescence spectroscopy with the use of the more informative range of exciting radiation: 230...310 nm. Only in this case the spectrum of natural water contains a protein fluorescence band in addition to humic matter and petroleum hydrocarbon fluorescent responses. The procedure and the result of computer decomposition of natural water spectra into basic contributions are presented in the paper. This information can be used for in situ measurements of fluorescence signals as well as for determination of organic matter concentrations.

Diagnostics of photosynthesizing organisms by linear and nonlinear fluorimetry

In the paper, the possibilities of classic and laser fluorimetry in photosynthesizing organisms (PSO) diagnostics are analyzed. Some special features of fluorescence of PSO excited by laser pulses are discussed. The results of research presented in the paper refer to the water PSO -- phytoplankton. However, some of them are valid for vegetation. Methods of linear and non-linear fluorimetry make it possible to determine the following parameters. (a) Fluorescence parameter (Phi) o equals Nflo/NRS, where Nflo is the photons number of photosynthesizing organism fluorescence without saturation effect, NRS is the number of Raman scattering photons from water molecules. (b) Parameter of photosynthetic activity (eta) equals Fv/Fm, where Fv and Fm are the intensities of variable and maximum fluorescence response. This parameter can be determined by the pump-and-probe technique. (c) Excitation cross-section of fluorophor (sigma) . This parameter depends on energy transfer form auxiliary pigments and reflects the group and species composition of algae. The cross-section (sigma) and other photophysical parameters of PSO can be determined by non-linear saturation spectroscopy. In principle, these parameters can be used for the diagnostics of PSO, i.e. for the determination of chlorophyll-a concentration, of photosynthesis efficiency and of phytoplankton species composition. In the paper the examples of spatial distributions of parameters (Phi) o, Nflo and (eta) obtained by ship lidar and by submersible biophysical probe are represented. The results obtained in some sea expeditions using lidars and double-flash submersible fluorimeter for phytoplankton diagnostics, are briefly analyzed.

Laser diagnostics of natural and pollution organic complexes in water environment

The possibilities of laser fluorescence spectroscopy for diagnostics of different kinds of organic substances such as petroleum hydrocarbons, humic substances, and proteins in natural water are discussed. The algorithm to determine the contributions of these organic complexes in fluorescence spectra from natural water are suggested and results of natural water monitoring during an expedition in the Black Sea are discussed.