Maximum Energy Difference Research Articles

ChemInform Abstract: Dynamics of Agostic Complexes of the Type C5R5(C2H4)M(CH2CH2‐μ‐H)+. Energy Differences Between and Ancillary Ligand Control of Agostic and Terminal Hydride Structures.

AbstractThe degenerate interconversions of the two enantiomeric forms of the agostic title complexes (M: Co; R: H, Me) via the sym. terminal hydrides (C5R5)Co(C2H4)2H+ are investigated by 13C NMR spectroscopy at 100.6 MHz in the temp. range ‐80 to ‐100 °C. The determined free energies of activation for this process (5.3 kcal/mol) represent a maximum energy difference between the agostic and terminal hydride structures.

Processing parameters for selective intermixing of GaAs/AIGaAs quantum wells

Some of the parameters which determine the amount of intermixing of GaAs/AIGaAs quantum wells (QWs) using SiO2 capping and rapid thermal annealing (RTA) have been studied using photoluminescence (PL) techniques. The degree of intermixing of QWs was found to be larger for thicker SiO2 capping layers and for shorter distances between the QWs and the oxide-wafer interface. A maximum PL energy difference of 90 meV was observed between the region covered by a 1.3 μm thick oxide layer and the non-oxide region in a wafer that was annealed at 1100° C for 15 s.

Thermochemical measurement of the ligand field splitting energies for hexaaquocopper(II) and hexaamminecopper(II)ions

The vacuum dehydration of copper(II) sulphate pentahydrate has been shown to pass through the transitory trihydrate state before proceeding to the monohydrate composition. Based on this, the heat of solution data for the high-energy modification hydrates have been reinterpreted and the low-energy crystalline hydrates of various compositions have been prepared and their heats of solution measured. From the heat of solution data the maximum energy difference expressed in kcal/mol heptahydrate appears to be of the right order of magnitude to be regarded as the ligand field splitting energy for the hexaaquocopper(II) ion. Similar measurement for the ammine complexes of copper(II) sulphate has also been done and the maximum energy difference was found to agree well with the value of LFSE obtained by spectroscopic method.