Transitional approximation

Compound CAS Registry Number Therm ochromic transition Approximate °C Spectral shift References... 

The UV-vis-NIR absorption spectra of newly isolated EMFs Ce2 C78 and Y2 C84 were recorded between 300 and 1100 nm in toluene solution. The spectrum of Y2 C84 (Fig. 4) is remarkably rich with characteristic absorption bands at 355, 482, 625, 710 and 785 nm. The onset of the absorption spectrum is at 785 nm and corresponds to the lowest energy electronic transition approximately the HOMO-LUMO energy gap. Figure 3 shows the UV-vis spectra of Ce2 C78 with several... 

It is important to point out that this coil-stretch transition mechanism for interfacial slip does not require the adsorbed chains to stay permanently anchored to the wall. The polymer melt adsorption only needs to be strong enough to keep adsorbed chains tethered onto the surface for as long as it takes for them to undergo the stress-induced coil-stretch transition. Approximately, this residence... 

Rydberg transition An electronic transition described approximately as promotion of an electron from a bonding orbital to a Rydberg orbital. Spectral bands corresponding to Rydberg transitions approximately fit the Rydberg formula... 

For both cross-over and parallel-design studies, sample collection time should be adequate to ensure completion of gastrointestinal transit (approximately 2-3 days) of the pharmaceutical product and absorption of the API. Blood sampling up to 72 hours following administration should be carried out, unless shorter periods can be justified. The number of subjects should be derived from statistical calculations, but generally more subjects are needed for a parallel study design than for a cross-over study design. 

E8.16 in aqueous solution at room temperature, molecular tumbling is fast compared to the timescale of the EPR transition (approximately gm gfh), and this removes the effect of the g-value anisotropy. We expect a derivative-type spectrum, possibly exhibiting hyperfine structure that is centred at the average g value. In frozen solution, g-value anisotropy can be observed because the spectrum records the values of g projected along each of the three axes, and the averaging from molecular tumbling does not apply. 

The problems in the crude or the transitional approximation arise from the fact that the stationary points of the integrals / are treated as isolated or as common points, respectively. The uniform approximation tries to map the exact behaviour into a simpler integral which is hoped to be understood in terms of known standard functions. The mapping function is determined... 

The theoretical description of the total cross section is easier in the semi classical limit since the angular range is indeed restricted to 9 = 0 so that the transition approximation gives results which are in quantitative agreement with those calculated by quantum mechanics. Using the parabola approximation for the phase shifts in the maximum or the straight line approximation for the deflection function at the zero point we have... 

Chromophore Transition Approximate wavelength of maximum absorption (nm)... 

While the uncoupled Hartree-Fock method and the single transition approximation have the merit of computational simplicity, they suffer, however, in particular from the usually unsatisfactory description of electronically excited states with a single-determinant wavefunction. 

A mixture of two incompatible polymers will have two separate transitions, as shown in Fig. 1.5(c). Each transition approximates to that of the constituent polymer. Much smaller changes in properties, termed minor or secondary transitions, often occur as well at lower temperatures than Tg. The impact resistance of the resin is usually superior when the temperature is above that of the secondary transitions. 

Emission transition Approximate wavelength glum value... 

Additional data on the melting points and enthalpies of fusion of SmCh (Laptev et al., 1976) and EuCl2 (Kulagin and Laptev, 1976) have appeared. Both dichlorides undergo polymorphic phase transitions approximately 90° below their melting points. The calibrated enthalpies of transition (4 1 kcal/mol) are substantial and thermochemical cycles for these systems should be reexamined in light of these results. 

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