Luminescence intrinsic

In inorganic solids, luminescence spectra can be categorized as intrinsic or extrinsic. Intrinsic luminescence, which appears at elevated temperatures as a near Gauss-ian-shaped band of energies with its peak at a photon energy is due to... 

A simplified schematic diagram of transitions that lead to luminescence in materials containing impurides is shown in Figure 1. In process 1 an electron that has been excited well above the conduction band et e dribbles down, reaching thermal equilibrium with the lattice. This may result in phonon-assisted photon emission or, more likely, the emission of phonons only. Process 2 produces intrinsic luminescence due to direct recombination between an electron in the conduction band... 

Intrinsic luminescence where an electron is excited from the valence band to the conduction band, so-called interband transition. Recombination of this electron with a hole in the valence band generates a photon, the energy of which corresponds to the energy difference of the band gap (Fig. 2.6a) ... 

Minerals of tin are capable of intrinsic luminescence, possibly connected with defect centers containing Sn T The ionic radius of Sn" " is of 0.83 A and the possible substituting luminescence center is Ti" " with an ionic radius of 0.75 A. 

Minerals of Ti are capable of intrinsic luminescence, which is connected with (TiOe) groups and a Ti + center. The ionic radius of Ti " is 0.75 A in 6-coordinated form. The possible substituting element is Cr + with an ionic radius of 0.76 A. 

The natural Mn minerals in our study consisted of four samples. The laser-induced time-resolved technique enables us to detect impurity and intrinsic luminescence of Mn " and Nd " " (Fig. 4.67). 

The possible luminescence of Eu " in scheelite is a very interesting problem. It was not detected by steady-state luminescence spectroscopy. The possible reason is that the very strong intrinsic luminescence of scheehte is situated in the same spectral range, which covers the weaker emission of Eu ". We tried to solve this problem by the time-resolved method using different decay times for intrinsic and Eu bands. Time-resolved spectroscopy... 

Center Sn " belongs to the 5s configuration. As an impurity in artificial phosphors it is mainly responsible for narrow luminescence bands from the UV to the red part of the spectrum. Besides that intrinsic luminescence of tin compounds is also known (Donker et al. 1989). 

In anticipation of the intrinsic luminescence properties of these polymeric materials incorporating polymetallic CuX substructures, we resynthesized the Cul and CuBr adducts with Et2S under similar reaction conditions to study the luminescence properties of these diethyl sulfide compounds. The presence of CU4I4 cubane clusters in the polymer could be easily detected by the very strong... 

Shevchuk and coworkers have performed systematic investigations of Ndm and Ybm 1 1 complexes with a series of calix[4]resorcinarenes and calix[4]arenes. A first study aimed at establishing an analytical procedure for the determination of these two ions in organic solvents. The intrinsic luminescence of the ligand is quenched when Ybm chloride is added to the so-... 

INTRINSICALLY LUMINESCENT METAL ORGANIC FRAMEWORKS (MOFs)... 

Luminescent multilayer systems have been reported extensively in Langmuir-Blodgett studies however, reports of intrinsically luminescent self-assembled multilayers are far rarer. Bard has reported on an intriguing luminescent multilayer comprised of alternate layers of 1,6-hexane dithiols and Cu ions (see Figure 5.59),... 

Ciprofloxacin in both the tablets and blood serum was determined by a fluorimetric method that was based on the intrinsic luminescence... 

Antharjanam PKS, Jaseer M, Ragi KN et al (2009) Intrinsic luminescence properties of ionic liquid crystals based on PAMAM and PPI dendrimers. J Photochem Photobiol A 203 50-55... 

Again it is noted that this method, in common with many others discussed above, requires the addition of a well-characterized probe molecule. Only a few studies have exploited the intrinsic luminescence properties of the polymer. The authors of some chemiluminescence studies described later attempted to use the changes in intrinsic photophysical and photochemical properties of the polymers as they cure to probe the viscosity and phase changes in the system. 

Cr(ox)3]3" as donor to the 2T state of [Cr(bpy)3]3+ as acceptor. For the case of intrinsic luminescence quantum efficiencies of close to unity for both donor and acceptor chromophores, the quantum efficiency of the energy transfer process can be calculated from the experimental spectra according to... 

The absorption edge shifts to the blue (Fig. 1). The photoluminescence has a broad band peaking at 640 nm. The luminescence line shape is not Lorentzian and has a strong Stokes shift. Photoluminescence excitation (PLE) spectra have revealed a fine substructure of the band at its short-wave wing whose origin is attributed to the intrinsic luminescence contribution and to radiative recombination on defects. 

This section. starts with the alkali halides, because the intrinsic luminescent center in these compounds shows a complicated relaxation in the excited state which has... 

CL detection can be used to probe intrinsic luminescence, such as that found in numerous biological systems (bioluminescence), or analytes of interest can be derivatized by reaction with an isothiocyanate or succinimidyl ester-linked chemiluminescent moiety. The first reported use of CL for CE detection was by Kara et who used peroxyoxolate as the luminophore to detect a... 

The majority of naturally occurring compounds are nonluminescent, including nucleic acids (DNA/RNA), mono- and polysaccharides, hpids, and most of the small biomolecules. Proteins contain in their structure three amino acids—phenylalanine, tyrosine, and tryptophan— that fluoresce in the UV range. Due to its long-wave emission and relatively low abundance, tryptophan is commonly used as an intrinsic luminescent probe to study proteins. Tryptophan also exhibits phosphorescence at room temperature. 

Different configurations and chemistries have been used in SPLS continuous procedures with increased advantages over the batch procedures, since it is possible with the former to use systems that are not possible with the latter. The luminescence signal can be obtained from temporary or permanent immobilization of the analyte or reaction product in the solid phase in the case of flow-through systems. The sensing schemes for intrinsic luminescent analytes are not very common because of the lack of intrinsic luminophors, such as with PAH, polychlorinated biphenyls, or trinitrotoluene. It is much more common to use different sensing schemes to obtain a luminescent event from a nonluminescent analyte. Among others are... 

In order to obtain an idea of the luminescence decay times and the intrinsic luminescent quantum yields of NIR luminescent lanthanide complexes. Table 2 compiles some typical decay times obtained in recent work. The decay times are much shorter than the luminescence decay times for Eu(III) and Tb(III), which are often on the order of himdreds of microsecmids. 

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