Constraints on the time scale of nuclear breakup from thermal hard-photon emission

Measured hard-photon multiplicities from second-chance nucleon-nucleon collisions are used in combination with a kinetic thermal model to estimate the breakup times of excited nuclear systems produced in nucleus-nucleus reactions at intermediate energies. The obtained nuclear breakup time for the ¹²⁹Xe + ^natSn reaction at 50 A MeV is Δτ ≈ 100-300 fm/c for all reaction centralities. The lifetime of the radiating sources produced in seven other different heavy-ion reactions studied by the TAPS experiment is consistent with Δτ ≈ 100 fm/c, such relatively long thermal photon emission times do not seemingly support the interpretation of nuclear breakup as due to a fast spinodal process for the heavy nuclear systems studied.     

C?C Bond Formation via Carbon-Centered Radicals Generated from Dicarbonyl(η5-cyclopentadienyl) organoiron Complexes

Irradiation of benzyldicarbonyl(η⁵-cyclopentadienyl)iron complex ( 2 ) leads to hemolytic cleavage of the Fe? C bond. In the presence of activated alkenes, radical addition occurs and both saturated and unsaturated addition products 7–9 are formed. Photolysis of alkyliron complexes 2 , 3 and 20 in the presence of acrylonitrile leads to the same products as the irradiation of the respective acyliron complexes 28–30 . This indicates that, under photolytical conditions, alkyl and acyl complexes are in equilibrium with each other.     

Formation of gold nanoparticles in gold ruby glass: The influence of tin

A ¹¹⁹Sn Mössbauer study was carried out of tin(IV) complexes with 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phenyl (H2Bz4Ph) derivatives: [Sn(2Bz4DH)Cl₃] (1), [Sn(2Bz4DH)PhCl₂] (2), [Sn(2Bz4M)Cl₃] (3), [H₂2Bz4M]₂[Ph₂SnCl₄] (4), [Sn(2Bz4Ph)PhCl₂] (5), [Sn(2Bz4Ph)Ph₂Cl] (6), in which H2Bz4R stands for the neutral ligand and 2Bz4R stands for the anionic thiosemicarbazone. In addition, ¹¹⁹Sn Mössbauer studies of the tin(IV) complexes [Sn(H4Bz4DH)₂Cl₄H₂O] (7), [Sn(H4BzPS)₂Cl₄H₂O] (8) with 4-benzoylpyridine thiosemicarbazone (H4Bz4DH) and the correspondent semicarbazone (H4BzPS) were performed. The isomer shifts decrease upon coordination due to the variation in the percentage of s character as tin changes from approximately sp³ hybridization in the tin salts to sp³d² in the octahedral or sp³d³ in the heptahedral complexes. The Mössbauer parameters of compound (4) showed the existence of two tin(IV) sites, which have been attributed to the presence of the cis and trans isomers.     

Large relativistic effects in molecular properties of the hydride of superheavy element 111

Relativistic and electron correlation contributions in the hydride of the recently discovered superheavy element 111 were studied using ab-initio methods within different relativistic approaches. Relativistic effects decrease the (111)H bond distance by 0.42 Å. As a result of this large bond contraction, the bond distance of (111)H (1.51 Å) is comparable to that of the hydride of its lighter congener AuH (1.52 Å), but below that of AgH (1.60 Å). The dissociation energy is relativistically increased by approximately 1.2 eV and the stretching force constant is more than quadrupled from 1.1 mdyn/Å at the nonrelativistic level to 5.0 mdyn/Å at the relativistic level.     

Reaction Kinetics and Chemical Quasi-Equilibria of the Ozone Synthesis in Oxygen DC Discharges

The spatial distribution of ozone and of oxygen atoms was studied along the active and the passive zone of a dc discharge (positive column, pressure: p = (4 … 10) · 10² Pa, current: I = 2 … 50 mA, flow rate: F = 5 … 100 sccm) in flowing oxygen. The composition of the final output O₂/O₃-mixture is controlled by relaxation processes in the passive reactor zone. It is affected sensitively by the total number density and the gas temperature in the afterglow. Steady states meaning reversible chemical quasi-equilibria were observed and analysed extensively. Within a detailed kinetic model the formation of these equilibria can be explained quantitatively. The synthesis to ozone is controlled above all by the metastable O₂ (a¹Δg) species, which modify drastically the results for the basic mechanism, considering the O atoms in the ³P and ¹D states.