scholarly journals The phosphorescence decay kinetics in the presence of a statistical distribution of molecules over the rates of radiative and non-radiative deactivation of triplet excitations

2020 ◽  
pp. 90-94
Author(s):  
N.V. Zhdanova ◽  
◽  
M.I. Deryabin ◽  
M.V. Erina ◽  
◽  
...  
Keyword(s):  
Rate Constants ◽  
Statistical Distribution ◽  
Decay Kinetics ◽  
Decay Function ◽  
Triplet Excitation ◽  
Heavy Atoms ◽  
Exponential Law ◽  
Phosphorescence Decay ◽  
Sensitized Phosphorescence ◽  
Approximate Formulas

Approximate formulas of phosphorescence decay kinetics under the conditions of the statistical scatter of molecules over rate constants of radiative or non-radiative deactivation of triplet excitation have been obtained. It is shown that the phosphorescence decay function has different form for these two cases. The obtained difference in kinetics was used to establish the reason for the deviation from the exponential law and faster decay of the sensitized phosphorescence of naphthalene and diphenyl in n-paraffin matrices ( T = 77 K) in the presence of heavy atoms in the donor.

scholarly journals Equilibrium of Phosphointermediates of Sodium and Potassium Ion Transport Adenosine Triphosphatase

1997 ◽  
Vol 109 (5) ◽  
pp. 537-554 ◽  
Author(s):  
Kuniaki Suzuki ◽  
Robert L. Post
Keyword(s):  
Ion Transport ◽  
Rate Constants ◽  
Adenosine Triphosphatase ◽  
Reaction System ◽  
Potassium Ion ◽  
Hydrolysis Rate ◽  
Decay Kinetics ◽  
Potassium Ion Transport ◽  
Pool Model ◽  
Sodium And Potassium

Sodium and potassium ion transport adenosine triphosphatase accepts and donates a phosphate group in the course of its reaction sequence. The phosphorylated enzyme has two principal reactive states, E1P and E2P. E1P is formed reversibly from ATP in the presence of Na+ and is precursor to E2P, which equilibrates with Pi in the presence of K+. We studied equilibrium between these states at 4°C and the effect of Na+ on it. To optimize the reaction system we used a Hofmeister effect, replacing the usual anion, chloride, with a chaotropic anion, usually nitrate. We phosphorylated enzyme from canine kidney with [32P]ATP. We estimated interconversion rate constants for the reaction E1P ⇌ E2P and their ratio. To estimate rate constants we terminated phosphorylation and observed decay kinetics. We observed E1P or E2P selectively by adding K+ or ADP respectively. K+ dephosphorylates E2P leaving E1P as observable species; ADP dephosphorylates E1P leaving E2P as observable species. We fitted a 2-pool model comprising two reactive species or a twin 2-pool model, comprising a pair of independent 2-pool models, to the data and obtained interconversion and hydrolysis rate constants for each state. Replacing Na+ with Tris+ or lysine+ did not change the ratio of interconversion rate constants between E1P and E2P. Thus Na+ binds about equally strongly to E1P and E2P. This conclusion is consistent with a model of Pedemonte (1988. J. Theor. Biol. 134:165–182.). We found that Na+ affected another equilibrium, that of transphosphorylation between ATP·dephosphoenzyme and ADP·E1P. We used the reactions and model of Pickart and Jencks (1982. J. Biol. Chem. 257:5319–5322.) to generate and fit data. Decreasing the concentration of Na+ 10-fold shifted the equilibrium constant 10-fold favoring ADP·E1P over ATP·dephosphoenzyme. Thus Na+ can dissociate from E1P·Na3. Furthermore, we found two characteristics of Hofmeister effects on this enzyme.

Time-Resolved Spectroscopy of Scintillation Materials using X-RAY Synchrotron Radiation

1994 ◽  
Vol 348 ◽  
Author(s):  
Andrey N. Belsky ◽  
Vitaly V. Mikhaihin ◽  
Andrey L. Rogalev ◽  
Eduard I. Zinin
Keyword(s):  
Synchrotron Radiation ◽  
Spectral Composition ◽  
Emission Spectra ◽  
Luminescence Spectra ◽  
Electronic Excitations ◽  
Decay Kinetics ◽  
Time Resolved ◽  
X Ray ◽  
Exponential Law ◽  
Kinetics Of

ABSTRACTThe time-resolved luminescence spectra and decay kinetics of BaF2, BGO, and CeF3, were measured with the dissector technique using X-ray synchrotron radiation (SR)of different spectral composition from wiggler mounted at VEPP-3 storage ring (Novosibirsk).Two effects of X-ray excitation energy on the luminescence parameters were observed: modifications of the emission spectrum and acceleration of decay kinetics. Under the excitation by soft X-ray SR the 220 nm emission band for BaF2 is broadened, whereas shorter wavelength part of CeF3 and BGO emission spectra increases. For luminescence decay of excitons and crossluminescence the degree of the deviation from the single exponential law depends on the photon energies and increases under soft X-ray excitation as well. These effects are supposed to be due to the interaction of electronic excitations created after the relaxation of deep core holes.Fast intrinsic luminescence was observed for Cdl2, and CsPbCl3 under X-ray SR excitation. 500 nm band of Cdl2 has characteristic time τ=4.6 ns, whereas 420 nm band of CsPbCl3 shows very fast decay with τ=0.2 ns.

Influence of triplet—triplet excitation transfer on the decay function of donor luminescence

1973 ◽  
Vol 20 (4) ◽  
pp. 376-378 ◽  
Author(s):  
Harumichi Kobashi ◽  
Toshifumi Morita ◽  
Noboru Mataga
Keyword(s):  
Excitation Transfer ◽  
Decay Function ◽  
Triplet Excitation

Spectra and Decay Kinetics of Diadamantyl-Dioxetane Chemiluminescence

1978 ◽  
Vol 33 (7) ◽  
pp. 763-769 ◽  
Author(s):  
Cornelia Neidl ◽  
Joachim Stauff
Keyword(s):  
Thermal Decomposition ◽  
Spectroscopic Methods ◽  
Radical Scavengers ◽  
Decay Kinetics ◽  
Thermally Induced ◽  
Decay Mechanism ◽  
Heavy Atoms ◽  
Induced Decomposition ◽  
Emitting Species ◽  
Kinetics Of

AbstractThe thermal decomposition of 1,2-diadamantyldioxetane was studied by kinetic and spectroscopic methods. Spectra of the chemiluminescence emitted during the thermally induced decomposition of 1,2-diadamantyldioxetane, tetramethyldioxetane and trimethyldioxetane were obtained and the influence of quenchers and radical-scavengers, and the presence of "heavy atoms" in the surrounding of the emitting species was investigated. The kinetics of the decay mechanism was followed by measuring the time dependence of the chemiluminescence. The influence of radical-scavengers, quenchers and "external heavy atoms" on the kinetics was assessed. Experimental results were discussed in terms of a biradical decay mechanism.

scholarly journals Reactions of Chlorine Dioxide with Organic Compounds

2016 ◽  
Vol 7 (1) ◽  
pp. 1 ◽  
Author(s):  
I.M. Ganiev ◽  
Q.K. Timergazin ◽  
N.N. Kabalnova ◽  
V.V. Shereshovets ◽  
G.A. Tolstikov
Keyword(s):  
Organic Compounds ◽  
Organic Synthesis ◽  
Chlorine Dioxide ◽  
Rate Constants ◽  
Drinking Water Treatment ◽  
Decay Kinetics ◽  
Reaction Rate Constants ◽  
Wide Range ◽  
Oxidation Of Organic Compounds ◽  
Number Of Publications

<p>Data on the reactivity of chlorine dioxide with organic compounds from various classes are summarized. Early investigations of the reactions of chlorine dioxide were occurred in aqueous or predominantly aqueous solutions in general, because it used in drinking water treatment and in industry as bleaching agent. However, chlorine dioxide was not used widely as reagent in organic synthesis. In last decades the number of publications on the studying interaction of the chlorine dioxide in organic medium increased. In table presented the rate constants reactions of chlorine dioxide with organic compounds published through 2004. Most of the rate constants were determined spectrophotometrically by decay kinetics of chlorine dioxide at 360 nm. Chlorine dioxide may be used for oxidation of organic compounds, because chlorine dioxide is enough reactive and selective as an oxidant with a wide range of organic compounds based on these reaction rate constants. But the application of chlorine dioxide as reagent in organic synthesis is restrained by the lack of data on the kinetics and mechanism of reactions involving chlorine dioxide, as well as data on the product yields and composition, temperature and solvent effects, and catalysts. The pathways of products formation and probable mechanisms of reactions are discussed in the review.</p>

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