Intensity-borrowing

Nolet MC, Beaulac R, Boulanger AM, Reber C (2004) Allowed and Forbidden d-d Bands in Octa-hedral Coordination Compounds Intensity Borrowing and Interference Dips in Absorption Spectra 107 145-158... 

The Kf matrix is related to the conventional K matrix of MQDT by a frame transformation from parabolic to spherical co-ordinates the K matrix is then related by a further frame transformation to the quantum defects [43, 45], The first term in Eq. (4) gives a contribution to the photoionization intensity borrowed from the bound-state spectrum. The dlyom term represents direct photoionization, and the overall expression allows Fano-type interference between these terms. In Eq. (5) A is a phase shift in the parabolic rep-... 

Using the intensity borrowing model, natural explanations now arise for the observations given above for the comparison of experimental and theoretical photoionization data of magnesium ... 

In the picture of spin-orbit perturbed Russell-Saunders states, the dipole transition moment of a spin-forbidden radiative transition is thus a sum of spin-allowed dipole transitions weighted by spin-orbit coupling coefficients (e.g., the expansion coefficients in Eq. [218]). The fact that the transition dipole moment of a spin-forbidden radiative transition is a weighted sum of spin-allowed dipole transition moments is exactly what experimentalists mean when they speak of intensity borrowing. The contribution of perturbing states to the oscillator strength can be positive or negative. In other words, per-turbers can not only lend intensity to a spin-forbidden transition, they can also take it away. 

The average phosphorescence radiative lifetime calculated with different basis sets vary between 23 (DZ) and 96 (TZ) seconds. The DZ and DZR results overestimate the T — So transition probability in unsaturated hydrocarbons their r values are too small. Discussion of these results has sense only in context of comparison with other molecules, but the absolute DZ values have no credit this basis set produces bad energies for a — 7T excitations, which are highly important for the T-S intensity borrowing. The best quality basis set (TZR) gives 64 seconds, which is much more credible. The so-called best experimental value is 30 seconds [154], but the proper estimation of non-radiative channels and the quantum yields still presents an open problem. From... 

The transition dipole mn in Eqs. [136] and [139] is the gas-phase adiabatic transition dipole. Therefore, emission intensities measured in different solvents should generate invariant transition dipoles when treated according to Eqs. [136] and [139]. A deviation from invariance can be used as an indication of the breakdown of the two-state approximation and the existence of intensity borrowing from other excited states of the chromophores (the Murrell mechanism T88,94j Figure 16 illustrates the difference between Eq. [139] and... 

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