Measurement of Luminescence

In bioluminescence and chemiluminescence reactions, light is emitted when the energy level of light emitter molecules falls from the excited state to the ground state. The quantum yield Q of the substance A is given by  

Calibration with luminol luminescence (Lee et al., 1966). Calibration with luminol can be performed in aqueous solution in the presence of H2O2 and a suitable catalyst (luminescence range 380-550 nm, Amax 430 nm), or in DMSO in the presence of potassium t-butoxide (A.mav 486 nm). The calibration method in aqueous medium requires the following three reagents  

Under the conditions described above, 1 ml of luminol solution of A347 1.0 will emit a total of 9.75 0.7 x 1014 photons. 

For monitoring the day-by-day fluctuation of the sensitivity of luminometer, the radioactive luminescence standard described by Hastings and Weber (1963), and Hastings and Reynolds (1966) is most useful and convenient (see also Section 2.6). 

Measurements of Coelenterazine, its Derivatives, and other Important Substances in Bioluminescence 

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Measurement of luminescence decay time represents another method of self-referencing. The method is widely used for the indicators that possess luminescence decay times in the microsecond and millisecond domain which can be interrogated... 

In order to implement frequency domain based sensing systems capable of monitoring the temporal luminescence of sensors, in few seconds, data must be collected at multiple frequencies simultaneously. Single-frequency techniques have been used to make frequency domain measurements of luminescent decays. 14, 23 28) This approach is unsuitable for real-time applications since data must be acquired at several frequencies in order to precisely and accurately determine the temporal variables of luminescent systems. 1 Each frequency requires a separate measurement, which makes the single frequency approach too slow to monitor the evolution... 

The bioluminescent direct contact flash test has been proposed as a modification of the direct contact luminescent bacterial test [24,38]. This method was developed for measuring the toxicity of solid and color samples, and involves kinetic measurements of luminescence started at the same time that the V. fischeri suspension is added to the sample. The luminiscence signal is measured 20 times per second during the 30 second exposure period. 

Measurement of luminescence lifetimes of the complexes in H20 and D20 solutions permits an estimate of the number of aqua ligands attached to the rare-earth cations. This was first carried out for complexes of Eu, Dy, Sm, and Tb with [SiWu039]8- and [PWii039]7 and indicated ca. 4-6 H2O for the 1 1 complexes and 0.1-0.5 H2O for the 1 2 complexes (Yusov and Fedoseev, 1988). More recent measurements have been reported for the 1 1 complexes of Eu with the a - and... 

The defect energy levels are also obtained from optical emission transitions. Measurements of luminescence in a-Si H are described in more detail in Chapter 8. Transitions to defects are observed as weak luminescence bands. The transition energies are about 0.8 eV and... 

This simple expression accounts well for the measurements of luminescence decay described in Section 8.3.3. This model only applies at low temperature because the multiple trapping mechanism is not considered. 

White, W.B., 1997, Precise measurement of luminescence banding profiles in speleothems for paleoclimatic interpretation, Proc. 12th Internatl. Congress Speleol. 1 89-92. 

Potential-dependent photoluminescence experiments provide information not only on quantum efficiencies but also on radiative or non-radiative recombination centres. Luminescence images of electrodes can be produced with the same set-ups that are used for photocurrent or microwave conductivity imaging, with the additional installation of a photodetector or photomultiplier for the measurement of luminescence. As with other imaging experiments, the observed images may show a luminescence distribution that depends strongly on applied electrode potential (see Section 12.8). 

Nickel, in a very useful paper, has discussed the elimination of polarization bias effects from the measurement of luminescence properties and transient absorption in isotropic solutions. The theoretical treatment is fully developed and recommendations are given for making reliable observations under a variety of experimental conditions are detailed. Determination of quantitative data from steady state luminescence spectroscopy is by no means as straightforward as many workers assume this work very convincingly demonstrates otherwise. 

Szabo has presented a uniEed and comprehensive analysis of diffusion controlled by molecular fluorescence quenching. Kopelman s review of fractals includes much of photochemical interest. Attention is drawn to Nickel s useful work on the theoretical and practical aspects of the measurement of luminescence properties, ere., under various experimental conditions. Scaiano has produced a valuable two-volume handbook covering all aspects of photochemical methodology. 

Steady-state and time-resolved luminescence measurements were carried out at room temperature. A nitrogen laser was used as an excitation source in measurements of luminescence decays. Time-resolved luminescence spectrally selected at 613 2 nm by a custom-made interference filter was detected using a FEU-83 photomultiplier tube and digitized by an ADC computer board. 

S. Cova, M. Bertolaccini, C. Bussolati, The measurement of luminescence waveforms by single-photon techniques, Phys. Stat. Sol. 18, 11-61 (1973)... 

Pulsed sources, including both lamps and lasers, are used for special apphca-tions such as dynamic measurements of luminescence lifetimes and time-resolved... 

Transient Absorption Spectroscopy Measurements of transient absorption spectra are much more difficult than the measurements of luminescence (PL) described thus far, especially for solid samples. However, time-resolved transient absorption spectroscopy has been used to study carrier dynamics in the... 

Techniques for the measurement of emission spectra and determination of luminescence quantum yields are well established and are presented in several books and review articles. In addition, Demas s 1983 book on measurement of luminescence lifetimes still serves as an excellent resource for general approaches. ... 

Bezman R, Faulkner LR (1972) Mechanisms of chemiluminescent electron-transfer reactions. VI. Absolute measurements of luminescence from the fluoranthene-10-methylphenothiazine system in N, N-dimethylformamide. J Am Chem Soc 94(18) 6331-6337... 

Knall et al. have tested a series of europium complexes with antenna chromo-phores in different polymer matrices in terms of sensitivity, response time, and dynamic range for the sensing of water vapor. A copolymer containing a Eu " chelate that can be spin-cast as thin film on glass slides was developed [110]. Scheme 6 shows the chemical structure of the polymerizable precursor 29. This complex can be copolymerized with norbomene-2,3-dicarboxylic acid dimethyl ester by means of ring opening metathesis polymerization. The sensor spots respond to water vapor by reversible luminescence quenching, which can be analyzed by means of phase sensitive measurements of luminescence lifetime [110]. 

Effective time-resolved measurement of luminescence emission would need a way to detect the emission only after the excitation. One way is to keep the light path to the detector closed during the excitation and then open it after the excitation. Another way is to inactivate the detector during the excitation and activate it after the excitation. Yet another method is to use a fast detector that can resolve the detection time for each detected photons and record the decay histogram of the luminescence emission intensity - thus allowing gating of the measurement. 

A sensitive light detector that can rapidly and repeatedly be activated and inactivated is an ideal detector for time-resolved measurement of luminescence intensity. Photomultiplier tubes (PMTs) in its variants and microchannel plates (MCPs) are detectors that fill these requirements to a large extent - and in practice the only... 

The accurate determination of the phase change between the excitation and emission waveforms is the central role in the frequency-domain measurements of luminescence. In the case of prompt fluorophores, the method of choice seems to be heterodyne detection - also called cross-correlation - and subsequent lock-in amplification. In the heterodyne detection, the gain of the photomultiplier is modulated by the frequency m Am where m is the frequency of the excitation modulation. As the consequence the PM signal contains a low-frequency... 

The power of the frequency-domain measurement of luminescence lifetimes of lanthanide derivatives is the excellent quality of data compared with the time-domain methods. This allows to use more sophisticated methods of data treatment... 

Measurement of luminescence provides the basis of highly sensitive assays for ATP. NADPH and Hj02- The production or disappearance of ATP can be measured by following light emission in the pre.scnce of fire-fly luciferase which catalyses the following reaction ... 

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