発熱型2重荷電交換反応4He(8He,8Be)4n による4中性子系の研究

学位の種別: 課程博士審査委員会委員 : (主査)東京大学講師 山口 英斉, 東京大学教授 小林 富雄, 東京大学教授 坂本 宏, 東京大学准教授 小沢 恭一郎, 東京大学教授 齊藤 直人University of Tokyo(東京大学

Grafting of adipic anhydride to carbon nanotubes through a Diels-Alder cycloaddition/oxidation cascade reaction

Accepted ManuscriptDifferent reactions have been reported for the successful functionalization of carbon nanotubes (CNT). The Diels-Alder cycloaddition is recognized as a plausible chemical approach, but few reports are known where this strategy has been used. In this study, the functionalization was performed by 1,3-butadiene generated from 3-sulfolene under heating conditions in diglyme. This simple and easily scalable method resulted in functionalized CNT with mass losses of 10 - 23 % by thermogravimetric analysis (nitrogen atmosphere). The functionalization was also supported by acid-base titration, elemental analysis, temperature programmed desorption and X-ray photoelectron spectroscopy. The high content in oxygen detected on the CNT surface was assigned to anhydride formation due to a cascade oxidation of the alkene groups generated in the cycloaddition reaction. The complete evolution of the alkene leads to a grafting density of 4.2 mmol g-1 for the anhydride moiety. Ab-initio calculations in CNT model systems indicate that the Diels-Alder addition of butadiene is a feasible process and that subsequent oxidation reactions may result in the formation of the anhydride moiety. The presence of the anhydride group is a valuable asset for grafting a multitude of complex molecules, namely through the nucleophilic addition of amines.Centro de Química and Instituto de Polímeros e Compósitos of the University of Minho and Fundação para a Ciência e Tecnologia (FCT) through the Portuguese NMR network (RNRMN), the Project F-COMP-01-0124-FEDER-022716 (ref. FCT PEst-C/QUI/UI0686/2011) FEDER-COMPETE, Project PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25-2013-2014) and also Project Scope UID/CEC/00319/2013. TG Castro acknowledges FCT for a doctoral grant (SFRH/BD/79195/2011) RF Araújo for a Post-doc grant (SFRH/BPD/88920/2012) and MMF also acknowledges FCT through the program Ciência 2008. Access to computing resources funded by the Project "Search-ON2: Revitalization of HPC infrastructure of UMinho" (NORTE-07-0162-FEDER-000086) is also gratefully acknowledged

Extending the Southern Shore of the Island of Inversion to F-28

Detailed spectroscopy of the neutron-unbound nucleus F-28 has been performed for the first time following proton/neutron removal from Ne-29/F-29 beams at energies around 230 MeV=nucleon. The invariant-mass spectra were reconstructed for both the F-27((*)) + n and F-26((*)) + 2n coincidences and revealed a series of well-defined resonances. A near-threshold state was observed in both reactions and is identified as the F-28 ground state, with S-n(F-28) = -199(6) keV, while analysis of the 2n decay channel allowed a considerably improved S-n(F-27) = 1620(60) keV to be deduced. Comparison with shell-model predictions and eikonal-model reaction calculations have allowed spin-parity assignments to be proposed for some of the lower-lying levels of F-28. Importantly, in the case of the ground state, the reconstructed F-27 + n momentum distribution following neutron removal from F-29 indicates that it arises mainly from the 1p(3/2) neutron intruder configuration. This demonstrates that the island of inversion around N = 20 includes F-28, and most probably F-29, and suggests that O-28 is not doubly magic

Intruder configurations in 29^{29}Ne at the transition into the island of inversion: Detailed structure study of 28^{28}Ne

Detailed $\gamma$-ray spectroscopy of the exotic neon isotope $^{28}$Ne has been performed for the first time using the one-neutron removal reaction from $^{29}$Ne on a liquid hydrogen target at 240~MeV/nucleon. Based on an analysis of parallel momentum distributions, a level scheme with spin-parity assignments has been constructed for $^{28}$Ne and the negative-parity states are identified for the first time. The measured partial cross sections and momentum distributions reveal a significant intruder $p$-wave strength providing evidence of the breakdown of the $N=20$ and $N=28$ shell gaps. Only a weak, possible $f$-wave strength was observed to bound final states. Large-scale shell-model calculations with different effective interactions do not reproduce the large $p$-wave and small $f$-wave strength observed experimentally, indicating an ongoing challenge for a complete theoretical description of the transition into the island of inversion along the Ne isotopic chain

Border of the island of inversion:Unbound states in Ne 29

The nucleus Ne29 is situated at the border of the island of inversion. Despite significant efforts, no bound low-lying intruder f7/2 state, which would place Ne29 firmly inside the island of inversion, has yet been observed. Here, the first investigation of unbound states of Ne29 is reported. The states were populated in Ne30(p,pn) and Na30(p,2p) reactions at a beam energy of around 230 MeV/nucleon, and analyzed in terms of their resonance properties, partial cross sections, and momentum distributions. The momentum distributions are compared to calculations using the eikonal, direct reaction model, allowing ℓ assignments for the observed states. The lowest-lying resonance at an excitation energy of 1.48(4) MeV shows clear signs of a significant ℓ=3 component, giving first evidence for f7/2 single particle strength in Ne29. The excitation energies and strengths of the observed states are compared to shell-model calculations using the sdpf-u-mix interaction.</p