Zero-field splitting assignment

MCD spectra can profitably separate contributions from multiple metal centres to a protein electronic spectrum, be used to evaluate metallo-biological systems without complications from the protein milieu , determine zero-field splitting, assign electronic transitions, provide information about a chromophore s electronic structure, evaluate theoretical models, obtain magnetic properties (g values, spin states, magnetic coupling) and be used for structural comparison of model and biological systems. 

Fig. 5. Energy level diagram for Pd(2-thpy)2 dissolved in n-octane. The Tj state at 18,418 cm is zero-field split on the order of 0.2 cm. The emission decay times refer to the individual triplet suhstates I, II, and III, respectively, at T = 1.3 K. (Compare Fig. 6.) These suhstates are radiatively deactivated as purely electronic transitions, as well as by Franck-Condon (FC) and Herzberg-Teller (HT) vibrational activity, respectively. This leads the different vibrational satellites. (Compare also Sects. 4.2.2 and 4.2.3.) The lifetime of the S, state is determined from the homogeneous linewidth of the spectrally resolved Sq —> S, electronic origin. (Sect. 3.2) The electronic state at 24.7 x 10 cm is not yet assigned...

Figure 25 compares the 1.3 K emission spectrum of perprotonated Pt(2-thpy)2 to that of the perdeuterated compound. The assignment of the spectrum of Pt(2-thpy-dg) follows that presented for Pt(2-thpy-hg)2. (See Sects. 4.2.1 and 4.2.4.) Both electronic origins I and II of Pt(2-thpy-dg)2 are blue shifted by (36 1) cm (see also Fig. 26). The same value is also found for origin III [23], showing that the relative splittings, i. e. the zero-field splittings, are maintained. Interestingly,...

Compound Lowest electronic origin 1 Zero-field splittings Emission decay times [ps] AEni Ti Til Tin sir time Tsir [ns] Assignments Remarks, References... 

The absolute positions of the doublet states are overestimated by about 2500 cm-1. The spin-orbit coupled emitting doublet states is predicted to be the 2A(3/2) component of the 2Eg state in agreement with spectral assignment but in conflict with excited state EPR experiments. Despite the quality of the calculations the large zero-field splitting (ZFS) of the 2Eg (220-290 cm-1) has not been reproduced with theoretical values less than 100 cm-1. 

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