Spectral intensity

Pelet, S., Previte, M. J. and So, P. T. (2006). Comparing the quantification of Forster resonance energy transfer measurement accuracies based on intensity, spectral, and lifetime imaging. J. Biomed. Opt. 11, 34017. 

Electron ionization is a perfect method for the analysis of labeled molecules as in this case ion-molecular reactions are suppressed. It is better to use for the calculations the most intense spectral peaks with the highest m/z values. Molecular ion is the best choice. However, if notable [M + H]+ or [M — H]+ peaks are present in the spectrum of the unlabeled compound the correct calculation will be problematic. To eliminate [M + H]+ peaks it is helpful to record a spectrum with the minimum quantity of sample. To consider interference with [M — H]+ ions one should know from what position the hydrogen atom is lost and whether deuterium could be in this position. 

The fragmentation processes of many molecules are very complex. For example normal butraldehyde, CH3 - CH2 - CH2 - CHO has its most intense spectral peak at 44. This has been explained by the following molecular rearrangement. 

The binuclear complex (9) may be produced from monomeric [V(nhet)] by two paths (i) by combination of two molecules of [V(nhet)(OH)]- or [V(nhet)(OH)]- and [V(nhet)(H20)],336 or (ii) by a cross-redox reaction between [Viv0(nhet)] and [Vn(nhet)] (see also Section 33.5.9.3).337,338 The unusually intense spectral features of [VnVIV0(nhet)2]2- originate in oxo bridging between V11 and V1 7 in the cross reaction.336-338 This intermediate has a short lifetime (—25 ms), but it is unusually long by comparison with other inner-sphere systems. 

While the question of stoichiometry requires further clarification, there is agreement that the intense spectral form represents two functionally important cobalt ions at the active site of the enzyme. Regardless of the existence of other specific sites, the spectral properties of the Co(II) enzyme offer the possibilities of selectively studying the catalytically essential metal-binding sites in this enzyme. Thus, the spectrum depends on pH, and its intensity decreases concurrently with the catalytic... 

Fig. 1. A low resolution diagram of the millimeter emission spectrum of Orion as seen by the Owens Valley Survey (Blake 1985). Selected intense spectral features are identified on the figure. Most of the weaker features have also been identified...

The fully saturated 1,3-dioxolanes and 1,3-oxathiolanes are conformationally labile rings and have been the subject of intense spectral investigation. In particular, 1,3-dioxolanes have a special place in NMR history. It was during a study of 4-substituted 2,2-dimethyl- 1,3-dioxolanes that geminal and vicinal couplings in aliphatic systems were shown to have opposite signs, a result which contradicted the theoretical predictions of the time (61JA3901). 

Reflection spectroscopy is used for more accurate quantification of the radiation reflected by a sample the intensity, spectral composition, angular distribution and polarisation can be analysed. This method is particularly apt for measuring samples that are impervious to light, that is to say, wherever absorption spectroscopy cannot be used. 

These can be performed successfully with AES. Indeed, the unambiguous detection and identification of a single non-interfered atomic spectral line of an element is sufficient to testify to its presence in the radiation source and in the sample. The most intensive line under a set of given working conditions is known as the most sensitive line. These elemental lines are situated for the various elements in widely different spectral ranges and may differ from one radiation source to another, as a result of the excitation and ionization processes. Here the temperatures of the radiation sources are relevant, as the atom and ion lines of which the norm temperatures (see Section 1.4) are closest to the plasma temperatures will be the predominant ones. However, not only will the plasma temperatures but also the analyte dilutions will be important, so as to identify the most intensive spectral lines for a radiation source. Also the freedom from spectral interferences is important. 

The IR and Raman spectra in Figure 3.6 were extracted from the images in Figure 3.5. These represent the fiber tracts (traces A and C) and the mesencephalon (traces B and D). The spectra contain more intense spectral contributions of lipids and cholesterol relative to the protein bands than the spectra of brain tumors in Figure 3.2. This is evident from the IR bands at 1060, 1234, 1382, 1467, 1740,... 

SIT, ISIT. Blooming will occur when diodes are saturated, i.e., signal will spill over to adacent diodes. This is partially reduced by the electrical isolation between adjacent diodes. Another phenomenon with similar results is halation or light reflected back to the photocathode from the target (the photocathode is semi-transparent). This is, in essence, a stray light phenomenon that produces an halo around high intensity spectral lines. 

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