G.M. Georgiev

Determination of Salts in Water Solutions by a Skewing Parameter of the Water Raman Band

The investigations of the Raman scattering from water show that information about the water temperature and the concentration of the dissolved salts is encoded in the band shape of the O-H stretching region 2800–3800 cm−1.

Concentration-dependence studies of Raman spectra of water by the method of self-deconvolution

Abstract The method of self-deconvolution is applied in Raman spectroscopy. The advantages provided by the polarized nature of the scattered light are discussed. The behaviour of the components in the composite Raman spectrum of water (OH-stretching region) versus the concentration of dissolved NaI and NaClO 4 salts is investigated. Effects which are impossible to observe by the widely used fitting procedures are also reported.

Application of laser induced saturation of molecular fluorescence for lifetime measurements

Abstract A technique for the determination of fluorescence lifetimes based on the laser induced saturation of molecular fluorescence is described. It allows lifetime measurements using exciting laser pulses longer than the lifetime under determination. The range of applicability of the technique is discussed and an experimental verification is carried out.

A new approach to the analysis of the effect of dissolved salts on the raman spectrum of water

Abstract The evolution of the Raman spectrum of water in the OH stretching region vs concentration of dissolved NaI, NaBr, NaBF 4 and NaClO 4 is investigated. The analysis of the intrinsically overlapping spectral components is accomplished by Fourier deconvolution. Particular attention is paid to the behaviour of the component arising from the anion—water interaction.

Raman study of the “free” OH groups in H2O-H2O2 mixtures using Fourier deconvolution technique

Abstract The frequency behaviour of the component at 3635 cm−1 in the Raman OH stretching spectrum of water, responsible for the so called “free· OH groups is studied for different concentrations of H2O2 in H2O up to 30 mole%. The water Raman band is decomposed by Fourier deconvolution technique (FDT) in the isotropic and anisotropic case. The increase in H2O concentration leads to a decrease in the frequency of the resolved component in both kind of spectra resulting in the apparent gradual vanishing of the high frequency shoulder in the original spectrum. The small frequency shift (35 cm−1) shows that “free” OH oscillators of water form weak hydrogen bonds with H2O2 and supports the idea of bifurcated H bonded weak associates of water molecules.

Temperature dependences of intra- and inter-molecular interactions in water and 12-Crown-4 - a comparison

Abstract Intra-, inter-molecular (inter-bond) and Fermi resonance interactions in water and 12-Crown-4 are considered. The temperature dependences of the corresponding interaction constants, recently published in literature (Refs. 1,2), are compared. It is shown that the main reason for the existing differences in the temperature behaviour of the intramolecular and Fermi resonance interactions between water and crown is the presence of strong temperature dependent H bonds between water molecules and an absence of such or similar bonds between crown molecules. The similarity in the temperature behaviour of the intermolecular (interbond) interaction in water and in crown is because of the similar mechanisms of the intermolecular (interbond) coupling.

Computerized laser Raman spectrometer

Abstract A microprocessor computer specially designed for application in optical spectroscopy is described and the construction of a laser Raman spectrometer realized on its base is discussed. The computer exercises an active control over a high resolution double monochromator, a photon counting system and the exciting laser radiation. The spectral information can be visualized on an oscilloscope display, hardcopied on a XY recorder and stored on magnetic tape.

Quantitative analysis of phytoplankton monocultures in vivo by laser excited fluorescence

Abstract Simultaneous registration of flourescence and Raman scattering spectra of diluted phytoplankton suspensions excited by a CW argon laser presents a convinient and sensitive technique for the quantitative analysis of photoplankton monocultures in vivo. Experimental verification of the technique is carried out and a linear correlation is established between a spectroscopic parameter and the quantitative characteristics of the suspensions.