KINETIC STUDIES ON CHEMILUMINESCENCE OF CHLOROPLASTS INDUCED BY CHANGES IN ION CONCENTRATION

Abstract— Acid-base, acid-, and salt-induced chemiluminescences of chloroplasts were investigated in relation to their dependences upon several time parameters:

• 1 The dependence of the three chemiluminescences on the preillumination time was similar; the luminescences rose to a maximum and then decayed to a steady-state This behaviour depends on the preillumination level and the length of the dark time following the preillumination. Analysis of the above indicates the formation of quenching entities during the preillumination which react with the luminescence precursors mainly in the dark. In contrast, the delayed light measured after 22 msec from the preillumination, showed a much slower but smooth rise to the steady-state with no subsequent drop.
• 2 During the dark period following preillumination the ability of the system to chemi-luminescence decayed with a first order rate.
• 3 During emission the above chemiluminescences decayed with a first order law. The total emission in different experiments was also proportional to the maximum emission, in agreement with a first order law of decay.
• 4 The comparison of the kinetic behaviour of the three types of chemiluminescence indicates common precursors of luminescence for at least the acid-base and the salt types. The delayed emission at 22 msec however, seems to have separate precursors than the three chemiluminescences.

     

Optimal magnetization in liquids,generated by triplet—doublet interaction

This study is an extension of a recent theoretical treatment for calculating the magnetization generated by the encounters of radicals and photoexcited triplets in solution. Whereas the previous study employed a restricted analytical approach to the problem, the present study takes into account a general numerical formulation for the solution of the stochastic Liouville equation to calculate the electron spin polarization generated in the radical, following its encounter with the triplet. This method considers the efficiency of triplet quenching by the radical, which is an important factor in determining the radical polarization and the triplet lifetime in the solution. In addition, numerical calculation of the diffusion process is used to obtain the overall magnetization of the radical and its time dependence. The theory presented here complies with the experimental results and allows for efficient optimization of the magnetization in terms of magnitude and overall lifetime. Such an optimization is accomplished by the proper choice of the chemical system, which is exposed to light excitation, solvent properties and temperature. The ultimate goal of this study is to achieve photo-controlled high magnetization, which can be used in a variety of novel microwave applications.     

OSCILLATIONS OF THE TRIGGERED LUMINESCENCES OF ISOLATED CHLOROPLASTS PREILLUMINATED BY SHORT FLASHES*

Abstract— Four types of triggered luminescence of isolated lettuce chloroplast (HCl-induced, methanol-induced, sodium benzoate-induced and T-jump-induced) were examined after preillumination by a series (from 1 to 10) of short flashes. Oscillations were observed in the luminescence peaks, with a period of four flashes. These oscillations had maxima after the second and the sixth flash, similar to those of delayed light emission. The maxima were shifted forward two flashes by 50 μ M hydroxylamine, as in oxygen evolution, and were abolished by 5 μ M DCMU, as for delayed light. These results may show that the mechanism of triggered luminescence is influenced directly by the oxidation states ( S ₁) on the donor side of photo-system II.