Decay properties of the 19/2− isomers in113,117Sb

By means of the generalized centroid-shift method, the following half-lives were determined:T _1/2(3045 keV)=3.7±0.3 ns in¹¹³Sb using the reaction¹⁰⁴Pd(¹²C,p2n) as well asT _1/2 (1322.8 keV)=3.5±0.3 ns,T _1/2(2779.8 keV) =0.50±0.15ns,T _1/2(2874.9 keV)<0.2 ns andT _1/2(3072.9 keV)<0.1 ns in¹¹⁷Sb using the¹¹⁶In(α, 2n) reaction. Three-quasiparticle configurations of the type πd _5/2ν(h_11/2 d _3/2) in^113,117Sb are found to dominate in the wave functions of the 19/2^? states at 3045 and 2780 keV in¹¹³Sb and¹¹⁷Sb, respectively. TheB(E2, 19/2^? → 15/2^?) values in^113–119Sb are discussed.     

A convenient synthesis of long-chain 4-substituted benzyloxycarbonyl alkanethiols for the formation of self assembled monolayers on metal substrates

New 4-substituted benzyl esters of 16-mercaptohexadecanoic acid were prepared by developing a practicable synthetic procedure and using readily available staring materials. The compounds synthesized have been characterized by NMR, MS, IR spectra and elemental analysis. The mercapto derivatives are precursors for the formation of self-assembled monolayers on metal substrates. Dedicated to Professor Dr. Manfred Hesse on the occasion of his 70 ^th birthday     

Transition probabilities and the structure of some negative-parity states in 126,130Xe and 132Ba

The lifetimes of several negative-parity states in ^126,130Xe and ¹³²Ba have been determined by means of the generalized centroid-shift method. The reactions ^124,128Te(α, 2n) and ¹²²Sn(¹³C, 3n) have been used. Following results were obtained: T_1/2(2758 keV) = 1.3 ± 0.2 ns in ¹²⁶Xe, T_1/2 (2060 keV) = 0.20 ± 0.10 ns, T_1/2 (2104 keV) = 0.50 ± 0.10 ns, T_1/2 (2376 keV) = 0.30 ± 0.10 ns and T_1/2 (2973 keV) = 4.6 ± 0.4 ns in ¹³⁰Xe as well as T _1/2(2120 keV) = 0.40 _?0.10 ^+0.20 ns in ¹³²Ba. A systematics of the B(E2; 7 ₁ ^? ? 5 ₁ ^? ) values in the N = 76 nuclei is presented. Electric dipole and quadrupole transition rates are discussed in terms of octupole and quadrupole collectivity. The structure of the 5 ₁ ^? and 7 ₁ ^? states is considered. Nuclear reactions: ^124,128Te(α, 2n), E = 26 MeV, ¹²²Sn (¹³C, 3n), E = 53 MeV; measured E_{gg}, I_{gg}, γ-r.f. Deduced T_1/2, B(σL) in ^126,130Xe and ¹³²Ba. Ge detectors. Generalized centroid-shift analysis.     

Some M1 transition strengths in odd-A nuclei away from closed shells

By the in-beam application of the generalized centroid shift method, nanosecond half-lives have been determined for the first time: in ${}^{101}\text{Pd}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(1337.4}\text{keV}\text{) = 1.2}{}^{\mathrm{+0.6}}{}_{\mathrm{?0.3}}\text{ns and}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(261.0}\text{keV}\text{) = 0.7 ± 0.2}\text{ns}$ using the reaction $\text{(}{}^{12}\text{C}\text{,x}\text{n}\text{)}$, in ${}^{71}\text{As}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(147.5}\text{keV}\text{) = 0.85 ± 0.25}\text{ns}$ using the reaction (¹⁶ O, αp), in ${}^{91}\text{Nb}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(5455.3}\text{keV}\text{) = 1.2 ± 0.3}\text{ns}$ using the reaction (¹⁶O,2np), in ${}^{103}\text{Pd}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(244.0}\text{keV}\text{) < 0.2}\text{ns}$ and in ${}^{91}\text{Nb}\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{(3110.2}\text{keV}\text{) < 0.2}\text{ns}$ using the reaction P(α, xn). Some known nanosecond isomers in different nuclei produced as by-products have also been detected. In the nuclei investigated far away from closed shells with complex wave functions, M1 transitions are considered which would be l-forbidden in the pure shell model. A retarded $\text{Ml}\text{(+}\text{E}\text{2)}\text{25}\text{2}{}^{\mathrm{+}}\text{→}\text{23}\text{2}{}^{\mathrm{+}}$ transition in ⁹¹ Nb is considered as proceeding between possible multiparticle-hole configurations.     

Redox properties and radical anions of fluorinated 2,1,3‐benzothia(selena)diazoles and related compounds

In comparison with 2,1,3‐benzothia(selena)diazoles, electrochemical oxidation and reduction of their 4,5,6,7‐tetrafluoro derivatives and a number of related compounds were studied by cyclic voltammetry. For nine examples of this class, the first reduction peaks are reversible and corresponding radical anions (RAs) are long‐lived at 295 K in MeCN and especially in DMF. The oxidation peaks were irreversible and corresponding radical cations were not observed. Electrochemically generated RAs were characterized by EPR measurements and DFT calculations at the UB3LYP/6‐31+G(d) level. The spin density distribution in the RAs is analyzed in connection with effects of S substitution by Se and/or H by F. The prospects of the studied RAs in the design and synthesis of magnetically active materials are discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation, crystallographic characterization and theoretical study of two isomers of C70(CF3)12

Two isomers of C70(CF3)12 have been isolated from a mixture obtained by trifluoromethylation of C70 with CF3I; their molecular structures determined by X-ray crystallography are in good agreement with the results of theoretical DFT calculations for the most stable C70(CF3)12 isomers.     

Thermodynamic and stress analysis of laser-induced forward transfer of metals

On the basis of a two-temperature model taking into account the laser-generated stress waves, we have performed an analysis of heating and melting dynamics in different metallic films (Au, Zn, Cr) irradiated by femtosecond laser pulses for the experimental conditions on laser-induced forward transfer. The modeling results have allowed puzzling out why, even within the same family of materials, substances can be transferred in the different phase states under rather similar laser-irradiation conditions.     

A model of nanosecond laser ablation of compound semiconductors accounting for non-congruent vaporization

We report a model of nanosecond laser ablation of compound semiconductors taking into account stoichiometry loss as a result of different volatilities of the material components. The model is based on the heat-flow equation for the bulk material and the diffusion equation for its atomic constituents and takes into account variations of material properties as functions of temperature and composition. Changing the optical response which results from stoichiometry violation is described within the concept of an effective medium and a multi-layer reflection model is applied. For cadmium telluride, as an example, the processes of ablation, melting, and resolidification under the action of a KrF laser have been studied in dynamics for particular experimental conditions in a wide range of laser fluences from the ablation threshold to the plasma shielding regimes described by the effective plasma plume representation. Multi-shot irradiation regimes have been investigated and the mechanism of the irradiation-controlled stoichiometry reversal has been elucidated.     

Modifications of 5,12-dihydroindolo[3,2-a]carbazole scaffold via its regioselective C2,9-formylation and C2,9-acetylation

The effective approaches for regioselective double formylation and acetylation of 5,12-dialkyl-6,7-diaryl-substituted 5,12-dihydroindolo[3,2-a]carbazoles by their treatment with dichloromethyl methyl ether in the presence of SnCl₄ or with acetyl chloride in the presence of AlCl₃ to afford the 2,9-diformyl or 2,9-diacetyl derivatives, respectively, were developed. Furthermore, new 2,9-bis(2,2-dicyanovinyl) derivatives were synthesized by the Knoevenagel condensation of diformyl-containing substrates with malononitrile, when new 2,9-bis(quinoxaline-2-yl)- and 2,9-bis(benzo[g]quinoxaline-2-yl) derivatives were formed via microwave-promoted oxidation of diacetyl-containing substrates with SeO₂ to the corresponding diglyoxals, followed by the reaction of these intermediates with o-phenylendiamine or 2,3-diaminonaphthalene, respectively. The basic optical and electrochemical properties of some 5,12-dihydroindolo[3,2-a]carbazoles were investigated.     

One-Pot Three-Component Synthesis of Polysubstituted Tetrahydroindoles

Chemistry of Heterocyclic Compounds - A series of novel fused pyrrole derivatives was synthesized by one-pot three-component reaction of β-enaminoketones, derived from cyclohexane-1,3-dione or...