Rigid motions in relativity

Starting with a simple characterization of pairs of rigidly joined straight world lines, successive generalizations are obtained up to the most general case which allows us to establish the various definitions of rigid motions in relativity (both special and general).     

A theoretical study of electrophilic substitution on aminophenols and aminobenzenethiols

Some electrophilic substitutions on aminophenols and amibenzenethiols have been studied taking into account the electrostatic perturbation caused by the attacker on the substrate molecule. The predicted reactions agree well with experimental results.     

High-spin states in 218Ra

Yrast states in ²¹⁸Ra up to spin and parity I^π = 17^? were identifíed by means of the ²⁰⁸Pb(¹³C, 3n) reaction and standard γ-ray spectroscopic techniques. The level scheme is characterized by two bands of opposite parity with nearly constant level spacing. A cascade of strong E1 interband transitions connects both bands.The results are discussed within the systematics of the even Ra isotopes. The negative-parity band which is observed from the I^π = 5^? to the I^π = 17^? state, is interpreted as an octupole vibrational band. The level scheme can be well reproduced in the vibrational limit of the interacting boson approximation (IBA1) which fails, however, to explain the strong E1 feeding of the negative-parity band from the ground-state band     

Stereospecific synthesis of γ-butyrolactones from acyclic vinyl sulfoxides: an asymmetric synthesis of optically pure oak lactones

The sulfoxide-directed lactonization of several trisubstituted vinyl sulfoxides with dichloroketene proceeds in a completely stereospecific manner. The lactonization of (E) -3 (R) -$\text{p}$-tolylsulfinyloctene occurs with complete enantiospecificity to produce a precursor for the synthesis of optically pure oak lactones.     

Quasiclassical dynamics simulation of the collision-induced dissociation of Cr(CO)6 + with Xe

Quasiclassical trajectory calculations are employed to investigate the dynamics of collision-induced dissociation (CID) of Cr(CO)6 + with Xe atoms at collision energies ranging from 1.3 to 5.0 eV. The trajectory simulations show that direct elimination of CO ligands, during the collision, becomes increasingly important as the collision energy increases. In a significant number of cases, this shattering mechanism is accompanied with a concomitant formation of a transient Xe-Cr(CO)x +(x<6) complex. The calculated results are in very good agreement with the experimental results presented previously [F. Muntean and P. B. Armentrout, J. Chem. Phys. 115, 1213 (2001)]. In particular, the computed cross sections and scattering maps for the product ions Cr(CO)x +(x=3-5) compare very favorably with the reported experimental data. However, in contrast with the conclusions of the previous study, the present calculations suggest that CID dynamics for this system exhibits a significant impulsive character rather than proceeding via a complex surviving more than a rotational period.