Energy luminescence

Keywords. Dendrimer, Antenna, Photon energy. Luminescence, Metal cation... 

FIGURE 2.1 Distribution of deposited energy among different degrees of freedom as a function of time, represented by pt = -log t (sec). Note that, for exothermic reactions, low-grade heat can terminate above the level of absorbed energy. Luminescence can only alter the picture in a minor way. Reproduced from Mozumder (1969a), by permission of John Wiley Sons, Inc. ... 

When heat is produced in the sample after the photolytic flash, the refractive index of the liquid changes and the probe beam is deflected. The intensity of this probe beam measured by a photomultiplier tube placed behind the pinhole decreases as the temperature of the irradiated volume increases (then its density and its refractive index decrease). The total optical signal change is a measurement of all the heat produced in the sample, i.e. the sum of non-radiative transitions, chemical reactions and solvation energies. Luminescence does not contribute to this signal (nor does scattered light) and for this reason thermal lensing can be used to determine luminescence quantum yields. 

The lower energy luminescence of Os(II) complexes relative to the corresponding Ru(II) complexes has led to a number of studies seeking complexes that absorb throughout the visible (black chromophores) and have emissive excited states in the near-infrared. Kol and Barigelletti reported the photophysical properties of Os(II) complexes of eilatin (eil, Scheme 1) and isoeilatin (ieil) bis-phenanthroline derivatives. The eil com-... 

Ambient pressure luminescence peaks and their pressure shifts for transitions from the 4fw 15d configurations to the ground state of the 4fw configuration. Values marked with an asterisk correspond to the onset of the lowest energy luminescence line. In the case of UO2, excitation energies were determined... 

Impossible to evaluate because the MLCT emission overlaps with a higher energy luminescence band (see text). 

To examine the relationship between the low-energy luminescence and intramolecular metal-metal distances, a series of [Pt2(CANAN)2(/U-L)]n+ (HCANAN=4-(aryl)-6-phenyl-2,2 -bipyridine) derivatives supported by different bridging ligands (L) have been prepared by Che and coworkers [17]. Subsequent spectroscopic assignments of cyclometalated platinum(II) or palladium(II) derivatives were made by comparing their emission energies with those of the [Pt2(CANAN)2(//-L)]n+ complexes. 

Fig. 8a-c Temperature dependence of the highest energy luminescence band of a [Gd(hfac)3NITBzImH] (solid lines) and [Eu(hfac)3NITBzImH] (dotted line, 5 K) b [Gd(NITBzImH)2(N03)3] (solid lines), [La(NITBzImH)2(N03)3] (dotted line, 5 K) c [Eu(NITBzImH)2(N03)3], absorption spectrum at 5 K shown as dotted line. Traces are offset along the ordinate for clarity... 

The luminescence of a-Si H has, in general, two emission bands, i.e., the band-edge luminescence, which peaks at 1.3-1.4 eV, and the low energy luminescence, which peaks at 0.8 eV [for reviews see Street (1981) and Chapter 7 by Street in Volume 21B]. 

It is proposed [11] that the high-energy luminescence band can be assigned to a a b3u->a electronic configuration change. The resulting excited states for... 

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