Luminescence absence

It should be noted that Cypridina luciferin emits a fairly strong chemiluminescence in aqueous solutions in the presence of various lipids and surfactants, even in the complete absence of luciferase. The luminescence is especially conspicuous with cationic surfactants (such as hexadecyltrimethylammonium bromide) and certain emulsion materials (such as egg yolk and mayonnaise). Certain metal ions (especially Fe2+) and peroxides can also cause luminescence of the luciferin. Therefore, great care must be taken in the detection of Cypridina luciferase in biological samples with Cypridina luciferin. 

Harvey (1952) noted R. S. Anderson has tested Aequorea at Friday Harbor and found that his hydromedusan will luminesce under strict anaerobic conditions. It was an extremely important observation retrospectively. The ability to luminesce in the absence of oxygen had been also observed with Medusa hemisphaerica by Macartney (1810) and with radiolarians, ctenophores, and Pelagia by Harvey (1926b). 

The spectra of the luminescence of coelenterazine catalyzed by recombinant Renilla luciferase in the presence and absence of Renilla GFP are shown in Fig. 4.6.3 (Lorenz et al., 1991). Note that the luminescence intensity at the emission peak is increased more than... 

Luminescence reaction (Bellisario et al., 1972). Mixing the luciferin, luciferase and H2O2 results in an emission of light, regardless of the presence or absence of molecular oxygen. The in vitro luminescence with partially purified luciferin and luciferase (A.max 503 nm) was spectrally similar to the in vivo luminescence from freshly exuded slime (A.max 507 nm) (Fig. 7.3.2). However, Ohtsuka et al. (1976) reported that the emission maximum was found at 490 nm when a pure sample of luciferin was used. 

Frequently, electrochemical information can be interpreted better in the presence of additional nonelectrochemical information. Typically, however, there is one significant restriction electrochemical and spectroscopic techniques often do not detect exactly the same mechanisms. With spectroscopic measurements (e.g., infrared spectroscopy), products that are formed by electrochemical processes may be detected. In other cases (luminescence techniques) mechanisms may be found by which charge carriers are trapped and recombine. Other techniques (electroreflection studies) allow the nature of electronic transitions to be determined and provide information on the presence or absence of an electric field in the surface of an electrode. With no traditional technique, however, is it... 

The first observations on the fluorescence of colloidal CdS were made using a colloid stabilized by colloidal silicon dioxide . The fluorescence spectrum consisted of a broad band with the maximum between 580 nm and 650 nm. The reproducibility of this red fluorescence was very poor. In the presence of excess Cd ions the intensity of the fluorescence was increased, which indicates that anion vacancies were centers of luminescence. Aging of the sol for a few weeks in the dark and in the absence of air was accompanied by an increase in fluorescence intensity by a factor of ten and a gradual red shift of the fluorescence band. However, even after this increase, the fluorescence quantum yield was still below 10 . ... 

In this paper we will describe and discuss the metal-to-metal charge-transfer transitions as observed in optical spectroscopy. Their spectroscopic properties are of large importance with regard to photoredox processes [1-4], However, these transitions are also responsible for the color of many inorganic compounds and minerals [5, 6], for different types of processes in semiconductors [7], and for the presence or absence of certain luminescence processes [8]. 

When the transient effect is negligible, k can then be determined by measuring the luminescence intensities under steady state conditions and the lifetimes of the decay in both the absence and the presence of a scavenger at concentration c. Indicating the intensities by Ig and I, respectively, and the... 

The lack of selectivity can be circumvented by coupling a postcolumn flow system to a liquid chromatograph. This has promoted the development of a number of efficient liquid chromatography-CL approaches [16, 17]. Eluted analytes are mixed with streams of the substrate and oxidant (in the presence or absence of a catalyst or inhibitor) and the mixed stream is driven to a planar coiled flow cell [18] or sandwich membrane cell [19] in an assembly similar to those of flow injection-CL systems. Many of these postcolumn flow systems are based on an energy-transfer CL process [20], In others, the analytes are mixtures of metal ions and the luminol-hydrogen peroxide system is used to generate the luminescence [21],... 

An alternative path includes oxidation, in the absence of light, of the diazaquinone with weak chemiluminescence (154). The effect of iron(II) on the luminescent intensity was interpreted by considering that it can efficiently generate the O - radical in a reaction with 02 and, as a consequence, increase the importance of reaction (108) in the overall process (155). 

Lifetime [3,9-11] based sensors rely on the determination of decay time of the fluorescence or phosphorescence. Typically, the fluorescence lifetime is 2-20 ps and phosphorescence lifetime is 1 ps to 10 s. Lifetime-based sensors utilize the fact that analytes influence the lifetime of the fluorophore. Thus all dynamic quenchers of luminescence or suitable quenchers can be assayed this way. The relationship between lifetimes in the absence (t0) and presence (t) of a quencher is given by Stern and Volmer ... 

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