Site-selective emission

Fig. 29 shows the spectra of the LaP04 Eu3+ (5%) core nanoparticles before a LaPCU shell was grown onto them. Site-selective emission spectra for the excitation at 17 294, 17 286, and 17 279 cm-1 correspond to the L-, M-, and H-sites in the bulk counterparts respectively. For comparison, no other site than L-, M-, and H-sites were identified in the site-selective emission spectra of Eu3+ LaPCU/LaPCU core-shell nanoparticles over the whole excitation range (17 249-17294 cm-1), indicating that these three sites are located in the interior of... 

Yersin, H. Donges, D. Nagle, J. K. Sitters, R. Glasbeek, M. Intraligand charge transfer in the Pd(II) oxinate complex Pd(qol)(2). Site-selective emission, excitation, and optically detected magnetic resonance. Inorg. Chem. 2000, 39, 770-777. 

The tools available for site selection include climatological data, topography, population data, emission inventory data, and diffusion modeling. Climatological data are useful in relating meteorology to emission patterns. For example, elevated levels of photochemical oxidant are generally related... 

As we will demonstrate, luminescent properties, radiative transition characteristics as well as emission under site selective excitation depend on the local environment s)rmmetry of the luminescent center. Therefore it is necessary to take into account and to describe the different local symmetry. There are two systems commonly used in describing symmetry elements of punctual groups ... 

In all cases the complexes were strongly luminescent at room temperature, in contrast to the precursor homonuclear derivatives, and at an energy that was tunable, displaying a site-selective excitation that depended on the Au Ag molar ratio, lying between the emission bands of the pure Ag and Au compounds. For instance, while the homonuclear derivative La[Ag(CN)2]3 emitted at 77 K at 345 and 470 nm (exc. 310 nm) and the gold complex La[Au (CN)2]3 at 431 and 493 nm (exc 310 nm), the mixed metal systems tended toward Ag or Au peak positions, depending on loading. 

Fig. 24. The RT emission spectra of the core-shell of Eu Y203/Al203 by site-selective excitation at Xexc = (a) 355, (b) 533.55, (c) 525.97, (d) 526.41 nm. The emission was detected using a boxcar integrator that averaged the signal from a cooled PMT with 15 ps gate and 0.3 ms delay from the pump laser pulse (redraw after (Chen, X.Y. et al.,...

The properties of the lowest triplet state of Pt(4,6-dFppy)(acac) in n-octane are nearly independent of the site chosen. An investigation of two other discrete sites reveals ZFS values which do not deviate significantly from the values observed for the main site. Furthermore, even different host materials do not lead to remarkable changes. Corresponding data are summarized in Table 1. For CH2C12 the splitting could be measured directly by site-selective spectroscopy of one discrete site, while for THF only a broadband spectrum was obtained. In this case, the ZFS was obtained from the temperature dependence of the thermalized emission decay time by a fit of (3) as described in Sect 3.2. 

Similarly to the situation found for Pt(4,6-dFppy)(acac) in /7-octane, several discrete sites are observed in the nonselectively excited emission spectrum of Ir(4,6-dFppy)2(acac) in CH2C12 at 4.2 K (not shown, but compare [50]). However, for the Ir(III) compound the inhomogeneously broadened background is much more intense. In Fig. 7, site-selectively excited emission spectra at different temperatures and a site-selectively detected excitation spectrum are displayed for the region of the electronic 0-0 transitions of the site of lowest energy, denoted as site A. 

Hole burning The photohleaching of a feature, normally a narrow range, within an inhomogeneous broader absorption or emission band. The holes are produced by the disappearance of resonantly excited molecules as a result of photophysical or photochemical processes. The resulting spectroscopic technique is site-selection spectroscopy. 

YBOsiEu vary with the synthetic route. The YBOaiEu powder synthesized through a sol-gel method exhibit three Eu sites identified by site selective excitation. The Eu concentration dependence of emission intensity and Eu luminescence decay from 300 to 15 K prove that the energy migration is phononassisted. (Boyer et al., 2003). 

Fig. 3. Emission spectra of Pd(2-thpy)2 (a) in an n-octane Shpol skii matrix (line spectrum) and (b) in butyronitrile (broad band spectrum) at T = 1.3 K, Aexc = 337.1 nm (N2-Laser). The energies of the vibrational satellites are specified relative to the electronic origin at 18,418 cm f The structures marked by asterisks on the high energy side of the electronic origin result from other sites and vanish with a site-selective excitation, e.g. at 19,113 cm (18,418 cm i -1-695 cm vibrational satellite). Concentration of Pd(2-thpy)2 10 mol/1. Note Fora better comparison, the broad band spectrum is shifted by 200 cm to lower energy. (Compare Ref. [56])...

Fig. 27. Emission spectrum of (b) Pt(2-thpy-h6)(2-thpy-d6) at T=1.3 K of site A. For comparison, the spectra of (a) Pt(2-thpy-hg)2 and (c) Pt(2-thpy-d6)2 are also reproduced. (Compare Fig. 25.) The compounds are dissolved in an n-octane matrix (= Shpol skii matrix) with a concentration of c = 10 mol/1. The compounds (a) and (c) are excited at Aexc = 457,9 nm (A 21,839 cm while the partially deuterated compound (b) is site-selectively excited at the elec-...

FIGURE 8.8. Site-selective photoluminescence spectra of para-hexaphenyl at 10 K emission spectra at excitation energies of 3.30 (top curve), 3.21, 3.14, 3.04, and 3.01 eV inset evolution of the emission peaks versus excitation energy the dotted line represents the quantum energy of the exciting photons.(Reproduced from Ref. 164. and 165.)... 

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