Lifetimes, table

The calculated lifetimes (Table 4) are several powers of ten larger then those corresponding to usual electric dipolar transitions (10- -10 s). They constitute therefore true predictions which require special techniques of measurements that were available only in recent years. 

Further proof of the importance of Franck-Condon factors is shown by the dramatically increased triplet-state lifetimes of aromatic hydrocarbons that have been deuterated. The effect of this deuteration is to decrease the rate of Ti A/W> S0 intersystem crossing, which is accompanied by a corresponding increase in triplet-state lifetime (Table 5.1). 

For single-tryptophan proteins there is some correlation between blue-shifted fluorescence emission maximum and phosphorescence lifetime (Table 3.2). Another correlation is that three of the proteins which exhibit phosphorescence, azurin, protease (subtilisin Carlsberg), and ribonuclease Tlt are reported to show resolved fluorescence emission at 77 K. Both blue-shifted emission spectra and resolved spectra are characteristic of indole in a hydrocarbon-like matrix. 

Slow decomposition sets in at about 500 K and the decomposition lifetime (Table 4.2) decreases with increasing temperature. The available residence time (Table 4.1) decreases and the decomposition fraction increases rapidly for temperatures greater than 800 K, and all the AEBCB is converted to propionitrile - - ethene by about 950 K. 

Advances in Alkylation Technology. Significant improvements have been made in the alkylation process during its 30 years commercial lifetime. Table III summarizes the major technical and mechanical advances. 

P-atom due to an inductive effect, hence destabilizing the HOMO. The LUMO of the chromophore Pd(CNR)2(P) is stabilized, going from a saturated chain P(CI I2) P to P—C=C—P, via coupling of the empty d orbitals located onto P and the empty ir-orbital located onto ethynyl fragment. The emission lifetimes in these polymers were surprisingly short (a few ns). Nevertheless, the quantum yields obtained are larger than expected for such short lifetimes (Table 5). This phenomenon remains unexplained. 

Actually, if H2O were the only cause of deactivation, this would imply that the lifetime of a given R(III) ion in all solvents (except water) should be close to its radiative lifetime. Table 1 shows that the solvated Eu(III) lifetime is solvent dependent (radiative Eu3+ lifetime 9.7 ms, from Carnall, 1979), tables 2 and 3 give a similar information for other R(III) solvated ions and Cm3+soiv, respectively. Examination of these tables shows that the contribution of D2O molecules to the deactivation pathways cannot be neglected, as that of any other solvent. 

As a summary to this section dealing with the measurement of fluorescence lifetimes, Table 1 gives some examples of lifetime determinations for some diatomic molecules. The majority of the studies cited in Table 1 have been made since 1975. The quantity of data available, even just for diatomic molecules, is large and it is impossible to include all lifetime measurements in such a brief table. However, the examples in Table 1 do give some impression of the wide range of species to which the techniques discussed above can, and have, been applied. 

This enhancement of intersystem crossing by combining heavy atom and paramagnetic effects explains the relative insensitivity of the Gd phosphorescence lifetime (Table IV) to any additional heavy atom effect (as in the chelate with iodo-BTFA), or to deuteration of solvent or ligand which, by inhibiting nonradiative deactivation, usually increases the lifetime of organic phosphorescence. This insensitivity of the lifetime of the Gd chelate permits us to assign the value of ca. 3 X sec." as the intrinsic radiative rate for the triplet state for Gd BTFA chelates, and a similar value should apply for the Eu compounds. 

The mean number of coordinated water molecules (n) for aqua ions and clathrochelates in aqueous solution and in the solid state was calculated from the excited-state lifetimes (Table 66). 

Keeping records of column backpressure and important chromatographic parameters [number of theoretical plates (AO, peak asymmetry factor (As), retention factor k ), resolution factor (Rs)] helps to monitor the required column performance, while storage in the appropriate organic solvent extends column lifetime. Table 8 presents the preventive actions for column protection. 

The intramolecular commimication along the Ca-axis generates two "divergent" R Cr energy transfer processes, as exemplified by the dramatic decrease in the Eu( Dq) lifetime (Table 31) which can be analyzed as follows, given the symmetry of the molecule and within the frame of the dipole-dipolar mechanism (Figure 127, bottom) ... 

Fluorescence intensity decay of the Trp residues can be described with four lifetimes (Table 7.1). 

Constructing W80N mutant leads to the abolishment of the shortest lifetime (Table 7.3). These results indicate that the shortest lifetime originates from tryptophan 80 and is the consequence of the high energy transfer Forster type from the tryptophan to the Fc4S4 cluster. 

The spin of the first excited state is confirmed by the isotropic (p—y) angular correlation, and the observed multipolarity (E2) of the radiation to the ground state. The lifetime (Table 3) is near that expected for the transition of a single proton. That a neutron transition should give such a value is probably due to collective motion. 

Each optical cable design normally undergoes a series of mechanical and environmental tests to ensure the cable performs as designed once deployed in the field. The tests are designed to simulate the installation, operating, and environmental conditions the cable will experience over its lifetime. Table 9.9 lists several tests typically performed on each cable design. In most tests, the acceptance criteria usually consist of attenuation measurements, visual inspections, or both. 

Radiative and radiationless processes have very different lifetimes (Table 1.1). The lifetime of an excited singlet state (10 -10 s) and triplet state (10 -10" s) is an important factor deciding the dissociation (cleavage) processes of an excited state (S and/or Tfj into free radicals. If the lifetime is very short, the above reaction is less probable. 

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