A new class of bimetallic isopropoxides of nickel(II) with niobium and tantalum with the general formula, Ni[M(OPri)6]2, (where M = Nb or Ta) have been synthesized by the reaction of nickel chloride isopropanolate, NiCl2·ϰPriOH, with potassium hexaisopropoxy metalates, KM(OPri)6, (M = Nb or Ta) in the molar ratio 1:2. These derivatives have been characterized by elemental analyses, molecular weight determinations, infrared and visible reflectance spectroscopy in addition to magnetic susceptibility measurements. Alcohol interchange reactions of these bimetallic alkoxides have also been studied. On the basis of above studies, an octahedral geometry has been assigned to Ni(II) in primary bimetallic alkoxides while in secondary derivatives, it appears that there exists an equilibrium between octahedral and tetrahedral forms.
In this paper the performance of a digital optical receiver consisting of an avalanche photodiode has been evaluated in the presence of noise and the intersymbol interference (ISI). The ISI levels have been computed for a multimode step index fiber for various lengths and data rates and the results are presented in the graphical form. Improvement in the receiver performance with an equalizer has also been worked out.
Some ternary and quaternary complexes of thorium(IV) with the general formula [Th(OOCCH3)2−n(SB)n(OOCC15H31)2] (HSB=Schiff bases and n=1 or 2) have been synthesized by the stepwise substitutions of acetate ions from thorium(IV) acetate, first with straight chain carboxylic acid and then with Schiff bases. The complexes are characterized by elemental analyses, spectral (electronic, infrared, 1H NMR, FAB mass, photoluminescence and powder XRD) and TEM studies. Conductance measurements indicated non-conducting behaviour of the complexes. Structural parameters from powder XRD data for complexes 5 and 6 which indicate poorly crystalline nano-sized triclinic particles. Electronic absorption spectra of the complexes showed π→π*
charge transfer transitions. All complexes displayed fluorescence and a correlation was sought between luminescence spectra of complexes in solution at room temperature. On the basis of physico-chemical studies, coordination number 8 was assigned for thorium(IV) in the complexes. The morphology and microstructure of the complexes were examined with transmission electron microscopy (TEM) and the selected area electron diffraction (SAED).