In a recent breakup-reaction experiment using a Be12 beam at 29 MeV/nucleon, the 0+ band head of the expected He4+He8 molecular rotation was clearly identified at about 10.3 MeV, from which a large monopole matrix element of 7.0±1.0 fm2 and a large cluster-decay width were determined for the first time. These findings support the picture of strong clustering in Be12, which has been a subject of intense investigations over the past decade. The results were obtained thanks to a specially arranged detection system around zero degrees, which is essential in determining the newly emphasized monopole strengths to signal the cluster formation in a nucleus.
Coordination polymers (CPs) are a class of crystalline solids that are considered brittle, due to the dominance of directional coordination bonding, which limits their utility in flexible electronics and wearable devices. Hence, engineering plasticity into functional CPs is of great importance. Here, we report plastic bending of a semiconducting CP crystal, Cu-Trz (Trz = 1,2,3-triazolate), that originates from delamination facilitated by the discrete bonding interactions along different crystallographic directions in the lattice. The coexistence of strong coordination bonds and weak supramolecular interactions, together with the unique molecular packing, are the structural features that enable the mechanical flexibility and anisotropic response. The spatially resolved analysis of short-range molecular forces reveals that the strong coordination bonds, and the adaptive C–H···π and Cu···Cu interactions, synergistically lead to the delamination of the local structures and consequently the associated mechanical bending. The proposed delamination mechanism offers a versatile tool for designing the plasticity of CPs and other molecular crystals.
An experiment for p( 14 C, 14 C * → 10 Be + α)p inelastic excitation and decay was performed in inverse kinematics at a beam energy of 25.3 MeV/u. A series of 14 C excited states, including a new one at 18.3(1) MeV, were observed which decay to various states of the final nucleus of 10 Be. A specially designed telescope-system, installed around the zero degree, played an essential role in detecting the resonant states near the α-separation threshold. A state at 14.1(1) MeV is clearly identified, being consistent with the predicted band-head of the molecular rotational band characterized by the π-bond linear-chain-configuration. Further clarification of the properties of this exotic state is suggested by using appropriate reaction tools.
Managing elastic properties of ABX3 type molecular perovskite ferroelectrics is critical to their future applications since these parameters determine their service durability and reliability in devices. The abundant structural and chemical viability of these compounds offer a convenient way to manipulate their elastic properties through a facile chemical approach. Here, the elastic properties and high‐pressure behaviors of two isostructural perovskite ferroelectrics, MDABCO‐NH4I3 and MDABCO‐KI3 (MDABCO = N‐methyl‐N′‐diazabicyclo[2.2.2]octonium) is systematically investigated, via the first principles calculations and high‐pressure synchrotron X‐ray diffraction experiments. It is show that the simple replacement of NH4+ by K+ on the B‐site respectively results in up to 48.1%, 52.4%, and 56.3% higher Young's moduli, shear moduli and bulk moduli, which is attributed to the much stronger KI coordination bonding than NH4…I hydrogen bonding. These findings demonstrate that it is possible to tune elastic properties of molecular perovskite ferroelectrics via simply varying the framework assembling interactions.
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