The effects of momentum conservation on pionization

The Mueller-Regge models of inclusive processes in the “pionization” region are constrained to obey momentum conservation. A seperate representation in the fragmentation region is found to be necessary on both theoretical and phenomenological grounds. It is also argued that the Laplace transform technique of solving the constraint equations highlights the bad low-energy behaviour of these models.     

Elastic behaviour near polymorphic transitions: Silver iodide

Longitudinal and transverse wave velocities have been determined as functions of pressure in polycrystalline silver iodide using the pulse transmission method. The velocities decrease with increasing pressure in the low pressure phase and increase with increasing pressure in the NaCl structure phase which is stable above 4 kbar at room temperature. The calculated value of the pressure derivative of the incompressibility of the low pressure phase is exceptionally low, sufficiently so to be inconsistent with some lattice dynamics formulations. The unusual properties of the low pressure phase may be due to the effect of Frenkel defects on elastic wave propagation.     

Fiber-optic infrared reflectance spectroelectrochemical studies of osmium and ruthenium nitrosyl porphyrins containing alkoxide and thiolate ligands

We have examined the redox behavior of the osmium and ruthenium compounds (OEP)M(NO)(OEt) and (OEP)M(NO)(SEt) (OEP = octaethylporphyrinato dianion; M = Os, Ru) by cyclic voltammetry and infrared spectroelectrochemistry. The compound (OEP)Os(NO)(OEt) undergoes a single reversible oxidation process in dichloromethane. In contrast, the thiolate compound (OEP)Os(NO)(SEt) undergoes a net irreversible oxidation resulting in formal loss of the SEt ligand. Extended Hückel calculations on crystal structures of these two compounds provide insight into the nature of their HOMOs. In the case of the alkoxide compound, the HOMO is largely metal centered, with 70% of the charge located in the metal's orbital and approximately 25% on the porphyrin ring. However, the HOMO of the thiolate compound consists of a pi bonding interaction between the metal dxz orbital and the px orbital on the sulfur, and a pi antibonding interaction between the metal d orbital and a pi* orbital on NO. The redox behavior of the Ru analogues have been determined, and are compared with those of the Os compounds.