Intensity of emission from

Fig. 8. Product yields and polarization (100 MHz) in the thermal decomposition (126°C) of 4-chlorobenzoyl peroxide (0-1 m) in hexachloroacetone containing iodine and water. Curve A, 4-ohlorobenzoic acid ([HjO], ca. 0-03 M) Curve B, p-chloroiodobenzene ([H2O], CO. 0-03 m) Curve C 4-chIorobenzoic acid ([HaO], ca. 1-6 m) Curve D, p-chloro-iodobenzene ([H O], ca. 1-6 m) Curve E, maximum intensity of emission from p-chloro-iodobenzene (O, co. 0-03 m H2O , ca. 1-6 M H2O). Data of Blank and Fischer, 1971b.

Scintillation The flash of light emitted when an electron in an excited state drops to a lower energy level. Scintillation counters are designed to measure the intensity of emissions from radioactive materials. 

Organic solvents enhance emitted intensities mainly because of a higher resultant flame temperature (water has a cooling effect), a more rapid rate of feed into the flame because of the generally lower viscosity, and the formation of smaller droplets in the aerosol because of reduced surface tension. The resultant enhancement of spectral line intensity may be 3-to over 100-fold. Conversely, the presence of salts, acids and other dissolved species will depress the intensity of emission from the analyte and underlines the need for careful matching of samples and standards. 

According to this definition the lifetime is the time required for the luminescence intensity to drop from 1(0) to /t = I (0)/e it should not be confused with the half-life often used for radioactive decays, this being the time t j2 required to decrease the intensity of emission from 1(0) to I (0)/2. 

A series of standard solutions are prepared and the intensity of emission determined for each concentration after zero setting of blank and hundred setting of the maximum concentration. The intensity of emissions from the test solutions is measured simultaneously and the concentration of the element is read from the calibration curve. 

Table IV gives the relative product distribution from the vacuum ultraviolet photolysis of ethyl chloride at 40 mm. pressure using the 1236-A. krypton resonance line. Owing to the low intensity of emission from the resonance lamp, higher pressures were not used in the photolysis experiments in order to prevent the major portion of the reaction from occurring in the region of the window where surface interactions are likely. Therefore, to provide a basis for more direct comparison between the photolytic and radiolytic yields, the radiolysis of ethyl chloride was also examined at 40 mm. pressure. The relative yields from several experiments of the latter study are given in Table IV. The lowest conversion yields from the radiolysis at the lower pressure show a relative distribution which is in close agreement with the relative product distribution detected from the radiolysis at 357 mm. Therefore, there is no substantial pressure effect on the decomposition product yields in ethyl chloride over the range 40-357 mm.

It is most important that the kinetics of the O -f NO -b M radiative reaction have been thoroughly studied. This is because the intensity of emission from this reaction has been measured absolutely, and it thus serves as a useful secondary actinometric standard for the determination of absolute intensities of other chemiluminescent processes. 

Recent work on the weak B-X bands in the bromine afterglow emission spectrum using improved spectral resolution indicates that the prominent transitions arise from vibrational levels, up to v = 9, of the B state of Br2. The energy of two P3/2 bromine atoms at 300 K lies just above = 1 of the B n(0+) excited state. The surprising observation of bands arising from v 9 is due to enhancement of the intensity of emission from these sparsely-populated levels at 300 K by the rapid increase in the Franck-Condon factors with increasing v in this spectral region. ... 

Intensity of Emission from the Vaience Band. In principle, the intensity of the electron emission from the valence state of the atom in the first-order process is determined by equations identical to those for the intensity of the emission from the core level [Eq. (23)]. The distinction lies in the matrix elements describing the atomic amplitude of this process. As mentioned above, the electron emission from the valence band may result from both the first- and the second-order processes. If the final state of the system formed as a result of these transitions is the same, these two processes must interfere. This interference is ignored in the present work. Such an approximation is justified by the fact that the final state of the system is determined by the secondary electron and the many-electron subsystem of the sample with a hole in the valence band. Neglect of the interference of the first- and second-order processes corresponds to the assumption that those processes give rise to different final states of the many-electron subsystem of the sample. Moreover, the contribution from the first-order processes of emission from the valence band is neglected in this work. The reason for that approximation is discussed in detail in Section 4. Thus, of all processes forming the spectrum of the secondary electron emission from the valence band of an atom, we shall consider only the second-order process. 

The intensity of emission from multiple-element hollow cathodes is generally lower than single-element tubes, although several successful combinations are possible if proper choice of elements is made, taking into account volatilization rates and noninterfering emission spectra. For example, a multiple-element combination of magnesium, calcium, and aluminum is available, as is a combination of silver, lead, and zinc. 

An alternative homogenous fluorescence-based detection system is fluorescence resonance energy transfer (FRET). This phenomenon occurs when two fluorophores are in close proximity, and the donor fluorophore has an emission spectrum that overlaps the excitation spectrum of the acceptor fluorophore. When the donor fluorophore is excited, energy is transferred from donor to acceptor with the result that the intensity of emission from the donor is reduced (quenched). If both the analyte and antibody are coupled to fluorophores with overlapping spectra, then FRET will occur only when the complex forms. Thus, FRET has not been applied widely in conventional immunoassays. 

Figure 8. Intensity of emission from an Ar/H2 plasma vs. wavelength.

The luminescence intensity of emission from a given level depends on the radiative and non-radiative probabilities. The quantum yields is expressed as... 

Such studies were focused, as a rule, on the energy changes of the atomic core levels and on the changes in structure of the valence state spectra of condensates when their composition alters during the deposition or under some treatment of the film (ionic bombardment, oxidation, etc.). It has been found by Kuznetsov (1990) that the formation of Ti-N and Ti-Al-N films is accompanied by charge transfer from the metal to the nonmetal atoms. The charge transfer is enhanced when the N content of the films increases. Analysis of the XES of the valence bands of Ti-Al-N films (Fig.. 8.11) leads to qualitative conclusions on the nature of chemical bonding in the condensate, where interatomic bonds are due to the overlap of Tid-Tid and Tid-Als,p-N2p states. Here, the intensity of emission from the hybridised p-d states decreases sharply as the film is depleted of N. 

The intensity of emission from the sample 7s(v, T) obtained by the method described above can be expressed by the following equation, where the reflectance of the sample is denoted by r v, T) and the intensity of emission from the trapping blackbody by /xb(v) (the temperature of the trapping blackbody is kept constant in all the measurements conducted... 

By denoting the intensity of emission from the true blackbody at a temperature the same as that of the sample by g(v, T), and by using Equation (15.7), Equation (15.13) may be... 

By observing the intensity of emission from vibrationally excited H Br formed in reaction (1.5b) as a function of the ratio of concentrations, [Br2]/[HI], Zaraga et were able to find the rate of the isotopic scrambling reaction... 

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