Two-dimensional fluorescence spectra

Allanic AL, Jezequel JY, Andre JC (1992) Application of neural networks theory to identify two-dimensional fluorescence spectra. Anal Chem 64 2618... 

Two-dimensional fluorescence spectra (2D) can be measured in three different ways ... 

Fig. 9.11 Two-dimensional fluorescence spectra of E. coli holo-(A) and apotryptophanase (B) in 100 mM potassium phosphate, pH 7.8. Fluorescence spectra were measured at 5-nm intervals of excitation wavelength and represented in contour. The two cross lines at the upper left-hand and lower right-hand comers in maps were due to primary and secondary scattering, respectively. Source Ref. 18...

A. L. Allanic, J. Y. Jezequel, and J. C. Andre, Anal. Orem., 64,2618 (1992). Application of Neural Networks Theory to Identify Two-Dimensional Fluorescence Spectra. 

A recent development has been the use of two-dimensional fluorescence spectroscopy as a new method for on-Hne monitoring of bioprocesses [108]. As ergot alkaloids fluoresce, the formation of the product during cultivation can be observed by two-dimensional fluorescence spectroscopy. Substraction spectra offered on-line real time information about the productivity during the cultivation. It was possible to follow the biomass concentration on-line by monitoring the culture fluorescence intensity in the region of riboflavine and its derivatives. This is a powerful application of this new sensor since the on-Une determination of biomass is extremely complicated for this fimgus. 

Total luminescence spectroscopy (TLS) is the simultaneous measurement of excitation, emission and intensity wavelengths of compound fluorophores [140-142]. This technique is mainly used for large ceU numbers in aqueous suspensions. In TLS the distinct fluorescence data that is generated from a three-dimensional matrix or excitation-emission matrix (EEM) of a specific microorganism is used for identification. Compared to two-dimensional emission spectra, this technique is highly sensitive and selective [143]. 

Several phenanthrenophanes Hsted in Table 19.2 were prepared after a structural examination of strain within the molecule using molecular mechanics (MM2) calculations. " Their predicted three-dimensional structures look much the same, but they actually are considerably different in reality. Evidence for the structural differences can be seen in the excimer emission behavior that is summarized in Table 19.3. Two typical fluorescence spectra are depicted in Figure 19.2. 

Time evolution of the ground state hole as well as fluorescence spectra initiated by a short pulse laser irradiation in solution has been conventionally explained in terms of the two-dimensional configuration coordinate model by Kinoshita . According to his theory, two adiabatic potential curves corresponding to the ground and excited states are assumed to have the same curvature but have the different potential minimum in the configuration coordinate. 

In order to analyze the spectral bands from the individual core complexes in more detail, we recorded the fluorescence-excitation spectra as a function of the polarization of the incident radiation. The excitation spectra have been recorded in rapid succession and the polarization of the excitation light has been rotated by 6.4° between consecutive scans. An example of this protocol is shown in the top part of Fig. 26.8a in a two-dimensional representation where 312 individual scans are stacked on top of each other. The horizontal axis corresponds to photon energy, the vertical axis to the individual scans, or equivalently to the polarization of the excitation, and the detected hu-orescence intensity is coded by the gray scale. The sum spectrum of these scans is presented at the bottom of Fig. 26.8a and shows two broad bands at 11,253 and 11,398 cm with a linewidth of 250 and 153 cm (FWHM),... 

Copyright (2003) with permission from Elsevier, (b) In situ XANES spectra at the Pt L3 of the PtRibo electrocatalyst held at 0.40 V in 1 M HCIO4 electrolyte solution. The spectra were obtained in a fluorescence mode. The spectra of the Pt foil used as a reference and in the calculation of the c/-band vacancies Insert in (b) shows a cubo-octahedral particle model for the electrocatalyst consisting of the Ru particle with two-dimensional Pt islands on its surface. Reprinted from Copyright (2004) with permission from Elsevier. 

Figure 31. a) X-ray fluorescence spectra and two-dimensional pXRD patterns (A = 1.968 A) from four selected points-of-interest for the nodule presented in Figure 30. b) pSXRD (negative contrast) maps of lithiophorite and goethite. c) One-dimensional pXRD patterns obtained by integrating intensities of 2D patterns at constant Bragg angle. ... 

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