Phosphorescence room-temperature

The aim of this work is the development of pyrene determination in gasoline and contaminated soils. For this purpose we used room temperature phosphorescence (RTP) in micellar solutions of sodium dodecylsulphate (SDS). For pyrene extraction from contaminated soils hexane was used. Then exttacts earned in glass and dried. After that remains was dissolved in SDS solution in the presence of sodium sulphite as deoxygenation agent and thallium (I) nitrate as heavy atom . For pyrene RTP excitation 337 nm wavelength was used. To check the accuracy of the procedures proposed for pyrene determining by RTP, the pyrene concentrations in the same gasoline samples were also measured by GC-MS. 

In room temperature phosphorescence, a treatment of the paper substrate with sodium dodecyl sulfate in conjunction with thallium acetate enhances the results and the technique can be used in routine environmental analysis of organic pollutants [156]. 

Solid-surface room-temperature phosphorescence (RTF) is a relatively new technique which has been used for organic trace analysis in several fields. However, the fundamental interactions needed for RTF are only partly understood. To clarify some of the interactions required for strong RTF, organic compounds adsorbed on several surfaces are being studied. Fluorescence quantum yield values, phosphorescence quantum yield values, and phosphorescence lifetime values were obtained for model compounds adsorbed on sodiiun acetate-sodium chloride mixtures and on a-cyclodextrin-sodium chloride mixtures. With the data obtained, the triplet formation efficiency and some of the rate constants related to the luminescence processes were calculated. This information clarified several of the interactions responsible for RTF from organic compounds adsorbed on sodium acetate-sodium chloride and a-cyclodextrin-sodium chloride mixtures. Work with silica gel chromatoplates has involved studying the effects of moisture, gases, and various solvents on the fluorescence and phosphorescence intensities. The net result of the study has been to improve the experimental conditions for enhanced sensitivity and selectivity in solid-surface luminescence analysis. 

Solid-surface luminescence analysis involves the measurement of fluorescence and phosphorescence of organic compounds adsorbed on solid materials. Several solid matrices such as filter paper, silica with a polyacrylate binder, sodium acetate, and cyclodextrins have been used in trace organic analysis. Recent monographs have considered the details of solid-surface luminescence analysis (1,2). Solid-surface room-temperature fluorescence (RTF) has been used for several years in organic trace analysis. However, solid-surface room-temperature phosphorescence (RTF) is a relatively new technique, and the experimental conditions for RTF are more critical than for RTF. 

Figure 2. (a) Room-temperature phosphorescence spectrum of benzo(e)pyrene on 80% a-cyclodextrin-NaCl in the presence of ben2o(a)pyrene. = 284 nm. (h) Room-temperature phosphorescence spectrum of benzo(e)pyrene on 80% a-cyclodextrin—NaCl. X - 284 nm. 

A linear plot indicates that the luminescence decay is exponential. The slope of the line gives kt, and rt can be calculated as above. The lifetime obtained by measuring the decay of P-type delayed fluorescence is equal to one-half the lifetime of the triplet state (see Section 5.2). Since in fluid solution at room temperature phosphorescence is generally much weaker than delayed fluorescence, the measurement of delayed fluorescence decay offers a convenient method for determining the lifetime of triplets at room temperature. 

Diaz-Garcia J., Costa-Femandez J.M., Bordel-Garcia N., Sanz-Medel A., Room-Temperature Phosphorescence Fiber-Optic Instrumentation for Simultaneous Multiposition Analysis of Dissolved Oxygen, Anal. Chim. Acta 2001 429 55-64. 

The biphenyl, naphthalene, pyrene, and triphenylene adducts display intense room-temperature phosphorescence.237 238 These observations indicate the occurrence of a mercury heavy atom effect, which promotes... 

SSRTP Solid surface room temperature phosphorescence... 

Fluorescence spectroscopy forms the majority of luminescence analyses. However, the recent developments in instrumentation and room-temperature phosphorescence techniques have given rise to practical and fundamental advances which should increase the use of phosphorescence spectroscopy. The sensitivity of phosphorescence is comparable to that of fluorescence and complements the latter by offering a wider range of molecules for study. 

Phosphorescence can also be detected when the phosphor is incorporated into an ionic micelle. Deoxygenation is still required either by degassing with nitrogen or by the addition of sodium sulphite. Micellestabilized room-temperature phosphorescence (MS RTP) promises to be a useful analytical tool for determining a wide variety of compounds such as pesticides and polyaromatic hydrocarbons. 

Room-temperature phosphorescence (RTP), dispersing the compound under investigation in a transparent polymer matrix such as Perspex... 

The fluorescence of purified histones has been studied by several different groups, 90 95) with the most detailed studies being on calf thymus histone HI. Histone HI, which binds to the outside of core particles, contains one tyrosine and no tryptophan. This protein exhibits a substantial increase in fluorescence intensity in going from a denatured to a folded state.<90) Collisional quenching studies indicate that the tyrosine of the folded HI is in a buried environ-ment.(91) Libertini and Small(94) have identified three emissions from this residue when in the unfolded state with peaks near 300, 340, and 400 nm. The 340-nm peak was ascribed to tyrosinate (vide infra), and several possibilities were considered for the 400-nm component, including room temperature phosphorescence, emission of a charge transfer complex, or dityrosine. Dityrosine has the appropriate spectral characteristics, but would require... 

It has been observed that for some proteins the room temperature phosphorescence lifetimes are increased in D20. The phosphorescence lifetime of liver alcohol dehydrogenase is 300 ms in H2Oand 500 ms in D2O.<10) Phosphorescence lifetimes are often dramatically increased by exchanging hydrogen with deuterium. The reason for this is that decay rates are affected by overtones of the C-H or N-H stretch. In the case of tryptophan in... 

Room temperature phosphorescence can be observed from dried proteins. Sheep wool keratin(47) has a phosphorescence lifetime of 1.4 s. Six lyophilized proteins were shown to exhibit phosphorescence at room temperature.(48) The spectra were diffuse, and the lifetime was non-single-exponential, which the authors interpreted as due to inhomogeneous distribution of tryptophans. As the protein was hydrated, the phosphorescence lifetime decreased. This decrease occurred over the same range of hydration where the tryptophan fluorescence becomes depolarized. Hence, these results are consistent with the idea that rigidity of the site contributes to the lifetimes. 

M. L. Saviotti and W. C. Galley, Room temperature phosphorescence and the dynamic aspects of protein structure, Proc. Natl. Acad. Sci. U.S.A. 71, 4154-4158 (1974). 

I. H. Leaver, On the room temperature phosphorescence of wool keratin, Photochem. Photobiol. 27, 439 143 (1978). 

G. B. Strambini, Singular oxygen effects on the room-temperature phosphorescence of alcohol dehydrogenase from horse liver, Biophys. J. 43, 127-130 (1983). 

Notwithstanding the excellent analytical features inherent in molecular phosphorimetric measurements, their use has been impeded by the need for cumbersome cryogenic temperature techniques. The ability to stabilize the "triplet state" at room temperature by immobilization of the phosphor on a solid support [69,70] or in a liquid solution using an "ordered medium" [71] has opened new avenues for phosphorescence studies and analytical phosphorimetry. Room-temperature phosphorescence (RTF) has so far been used for the determination of trace amounts of many organic compounds of biochemical interest [69,72]. Retention of the phosphorescent species on a solid support housed in a flow-cell is an excellent way of "anchoring" it in order to avoid radiationless deactivation. A configuration such as that shown in Fig. 2.13.4 was used to implement a sensor based on this principle in order to determine aluminium in clinical samples (dialysis fluids and concen-... 

Photoinduced electron transfer from eosin and ethyl eosin to Fe(CN)g in AOT/heptane-RMs was studied and the Hfe time of the redox products in reverse micellar system was found to increase by about 300-fold compared to conventional photosystem [335]. The authors have presented a kinetic model for overall photochemical process. Kang et al. [336] reported photoinduced electron transfer from (alkoxyphenyl) triphenylporphyrines to water pool in RMs. Sarkar et al. [337] demonstrated the intramolecular excited state proton transfer and dual luminescence behavior of 3-hydroxyflavone in RMs. In combination with chemiluminescence, RMs were employed to determine gold in aqueous solutions of industrial samples containing silver alloy [338, 339]. Xie et al. [340] studied the a-naphthyl acetic acid sensitized room temperature phosphorescence of biacetyl in AOT-RMs. The intensity of phosphorescence was observed to be about 13 times higher than that seen in aqueous SDS micelles. 

The room temperature phosphorescence spectra of benzophenone and its substituted analogues show a weak band about 1600 cm -1 higher in frequency than the first phosphorescence band. Because the temperature dependence of its intensity corresponds to an activation energy approximately equal to the... 

Luminescence spectrophotometry consists of fluorescence, phosphorescence and low-temperature total luminescence. Fluorescence is generally measured at room temperature. Phosphorescence is generally observed at liquid nitrogen temperature (77K) with the aid of a chopper to interrupt the exciting radiation. Total luminescence is the combined fluorescence and phosphorescence obtained at low temperature (77K). Luminescence spectrophotometry is generally much more sensitive and specific than absorption spectrophotometry. 

Methods based on photoactivated luminescence [193] and room-temperature phosphorescence [194] have been used to determine polychlorobiphenyls in soil. 

Surfactants were found to induce phosphorescence from 1-bromonaphthalene in aerated aqueous solutions of (3-CD [22], In the case of the 1 1 inclusion-complex formation between 7-cyclodextrin and acenaphthene in aqueous solution, bromoalcohols such as 2,3-dibromopropane-l-ol or 2-bromoethanol induced a decrease of the fluorescence and an enhancement of room-temperature phosphorescence of acenaphthene [23],... 

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