化学学科核心素养指引下的“配合物”教学探讨

指出了高中阶段“配合物”教学中存在的问题,并从“应用杂化轨道理论解决配合物中心部分的空轨道问题”“尝试判断配位原子”“用平衡思想理解配合物的内界组成”等3个方面阐述了如何在化学学科核心素养的指导下引导学生更好地进行配合物知识的学习。     

Engineering the Atomic Interface with Single Platinum Atoms for Enhanced Photocatalytic Hydrogen Production

It is highly desirable but challenging to optimize the structure of photocatalysts at the atomic scale to facilitate the separation of electron–hole pairs for enhanced performance. Now, a highly efficient photocatalyst is formed by assembling single Pt atoms on a defective TiO₂ support (Pt₁/def‐TiO₂). Apart from being proton reduction sites, single Pt atoms promote the neighboring TiO₂ units to generate surface oxygen vacancies and form a Pt‐O‐Ti³⁺ atomic interface. Experimental results and density functional theory calculations demonstrate that the Pt‐O‐Ti³⁺ atomic interface effectively facilitates photogenerated electrons to transfer from Ti³⁺ defective sites to single Pt atoms, thereby enhancing the separation of electron–hole pairs. This unique structure makes Pt₁/def‐TiO₂ exhibit a record‐level photocatalytic hydrogen production performance with an unexpectedly high turnover frequency of 51423 h^?1, exceeding the Pt nanoparticle supported TiO₂ catalyst by a factor of 591.     

Quantum Emulation of Extreme Non‐Equilibrium Phenomena with Trapped Atoms

Ultracold atomic physics experiments offer a nearly ideal context for the investigation of quantum systems far from equilibrium. We describe three related emerging directions of research into extreme non‐equilibrium phenomena in atom traps: quantum emulation of ultrafast atom‐light interactions, coherent phasonic spectroscopy in tunable quasicrystals, and realization of Floquet matter in strongly‐driven lattice systems. We show that all three should enable quantum emulation in parameter regimes inaccessible in solid‐state experiments, facilitating a complementary approach to open problems in non‐equilibrium condensed matter.     

Oriented O(3P2), Ne(3P2), and He(3S1) atoms emerging from a bent magnetic guide

We describe our observation of strongly oriented total electronic angular momentum J in O(³P₂), Ne(³P₂), and He(³S₁) atoms emerging from a bent magnetic multipole guide, as measured by resonant multiphoton ionisation. This was contrary to our expectation because no additional (uniform) magnetic fields were applied to orient the atoms behind the exit of the guide. Two- and three-photon ionisation techniques were employed to determine the degree of J polarisation, from which we infer that atoms become oriented as a result of a combination of weak fringe fields, possible stray fields, and the fact that molecular beam packets do not oscillate around the geometric center of the bent multipole guide. We conclude that similar effects may exist in other, related experiments and that a detailed characterisation of the degree of orientation is required prior to any study of chemical dynamics or spectroscopy. This paper should serve as a warning for anybody using similar devices not to assume isotropic angular momentum distributions of atoms and molecules emerging from a magnetic guide or a decelerator, particularly when it is bent; whenever possible, the possibility for a J anisotropy should be experimentally checked.     

A chronological test of ocean-bottom spreading in the North Atlantic

Fission-track and K-Ar dating of basaltic glass from the Mid-Atlantic Ridge gives results which are consistent with the proposal of ocean-floor spreading. Correlation exists between the magnetic anomaly patterns over the Crest Mountains at 45°N and the age of the outcropping basalts. The observed sequences of ages progressing outward from the Median Valley 11,000, 230,000, 310,000, 750.000, 8,000,000, and 16,000,000 years constitute strong, direct support for the idea of ocean-bottom spreading.     

Anabiosis of phase distribution of a three-level atom

We study the phase probability distribution of a three-level atom interacting with a cavity field in the presence of two-photon detuning and decoherence. Anabiosis of the phase probability distribution is observed due to the presence of the Stark shift. The simulation demonstrates that there is an enhancement of the phase sensitivity as soon as the two-photon detuning is considered. The W-Wigner function is also examined and it is shown that the nonclassical effect is apparent, however, for a small value of the decoherence factor.     

The dynamics of triple-well trapped Bose-Einstein condensates with atoms feeding and loss effects

In this paper, we consider the macroscopic quantum tunnelling and self-trapping phenomena of Bose-Einstein condensates （BECs） with three-body recombination losses and atoms feeding from thermal cloud in triple-well potential. Using the three-mode approximation, three coupled Gross-Pitaevskii equations （GPEs）, which describe the dynamics of the system, are obtained. The corresponding numerical results reveal some interesting characteristics of BECs for different scattering lengths. The self-trapping and quantum tunnelling both are found in zero-phase and ：r-phase modes. Furthermore, we observe the quantum beating phenomenon and the resonance character during the self-trapping and quantum tunnelling. It is also shown that the initial phase has a significant effect on the dynamics of the system.