The strength distributions of the giant monopole resonance (GMR) have been measured in the even-A Sn isotopes (A=112-124) with inelastic scattering of 400-MeV alpha particles in the angular range 0 degrees -8.5 degrees . We find that the experimentally observed GMR energies of the Sn isotopes are lower than the values predicted by theoretical calculations that reproduce the GMR energies in 208Pb and 90Zr very well. From the GMR data, a value of Ktau = -550 +/- 100 MeV is obtained for the asymmetry term in the nuclear incompressibility.
We have investigated the isoscalar giant resonances in the Sn isotopes using inelastic scattering of 386-MeV α-particles at extremely forward angles, including 0 • . We have obtained completely "background-free" inelastic-scattering spectra for the Sn isotopes over the angular range 0 • -9 • and up to an excitation energy of 31.5 MeV. The strength distributions for various multipoles were extracted by a multipole decomposition analysis based on the expected angular distributions of the respective multipoles. We find that the centroid energies of the isoscalar giant monopole resonance (ISGMR) in the Sn isotopes are significantly lower than the theoretical predictions. In addition, based on the ISGMR results, a value of K τ = −550 ± 100 MeV is obtained for the asymmetry term in the nuclear incompressibility. Constraints on interactions employed in nuclear structure calculations are discussed on the basis of the experimentally-obtained values for K ∞ and K τ .2
2-Azulenyl trifluoromethanesulfonate was prepared by the reaction of 2-hydroxyazulene with trifluoromethanesulfonic anhydride in the presence of triethylamine as a base. Under the use of pyridine, 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate further reacted with 2-azulenyl trifluoromethanesulfonate to give 1-(1-trifluoromethanesulfonyl-1,4-dihydropyridin-4-yl)azulenyl trifluoromethanesulfonate. Moreover, we found that azulenes also reacted with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate to give 4-(1-azulenyl)-1,4-dihydropyridine derivatives and 6-(1-azulenyl)-1-trifluoromethanesulfonyl-1-aza-hexa-1,3,5-triene depending on the reaction conditions. 2-Azulenyl trifluoromethanesulfonate was converted finally into the parent azulene in excellent yield by palladium-catalyzed reduction using formic acid as a reducing reagent.
The compression-mode isoscalar giant monopole resonance (ISGMR) has been studied in the Sn, Cd and Pb isotopes using inelastic scattering of 400 MeV α-particles at extreme forward angles, including .We have obtained completely ``background-free'' inelastic-scattering spectra for the Sn, Cd, and Pb isotopes for a wide angular and excitation-energy range. The various giant resonances excited with different transferred angular momenta were extracted by a multipole-decomposition analysis (MDA). It was found that the centroid energies of the ISGMR in Sn isotopes are significantly lower than the theoretical predictions. The K τ in the empirical expression for the nuclear incompressibility has been determined to be MeV from the moment ratios [1]. The extracted value for the Cd isotopes isMeV. These numbers are consistent with values of MeV obtained from an analysis of the isotopic transport ratios in medium-energy heavy-ion reactions [2], MeV obtained from constraints placed by neutron-skin data from anti-protonic atoms across the mass table [3], and MeV obtained from theoretical calculations using different Skyrme interactions and relativistic mean field (RMF) Lagrangians [4].Stringent constraints on interactions employed in nuclear structure calculations are obtained on the basis of the experimentally determined values for and . These parameters constrain as well the equation of state (EOS) of nuclear matter. However, a significant discrepancy still remains. The ISGMR positions in Sn and Cd isotopes are systematically lower than the predictions obtained on basis of determined from the ISGMR in 208 Pb. This raises the question "why are Sn and Cd nuclei so soft?", an important problem that has to be solved [5]. For a clue to solve the problem, the exact positions of the ISGMR in 204, 206, 208 Pb have to be measured [6].In this talk, we will review the current status of the experimental studies on the compressionmode giant resonances, and the possible implications for astrophysics and physics with exotic nuclei.[1] T. Li et al., Phys.
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