Junrong Li

Quantum interference effect on collisional energy transfer within singlet∼triplet mixed states of Na2 (v=8)∼(v=14)

Abstract In a previous study [G.-H. Sha, B. Jiang, J.-B. He, C.-H. Zhang, J. Chem. Phys. 102 (1995) 2772], the first evidence for collisional quantum interference (CQI) in intramolecular energy transfer within CO singlet∼triplet mixed states was obtained. We present here another evidence for CQI effect on energy transfer within the singlet∼triplet mixed states of Na2 ( A 1 Σ + u , v=8xa0∼xa0 b 3 Π 0 u , v=14)+Na(3s) by optical–optical double resonance fluorescence spectroscopy. The measured state-to-state cross-sections show the unique feature of abnormal ΔJ-dependence of cross-sections due to constructive or destructive interference. Molecular rotation speed and interaction potential have important effect on the extent of interference.

Serration behaviours in metallic glasses with different plasticity

Abstract We present a statistical study of serration behaviours in Pd77.5Cu6Si16.5, Ti41Zr25Be26Ag8, Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 and Fe50Ni30P13C7 metallic glasses with different plasticity. The four samples show similar serration patterns in the beginning of yielding, and different patterns during later loading. These results indicate that the shear band initiation process in metallic glasses follow some similar dynamics. And the later serration process follows different dynamics and will lead to different plasticity. Here we interpret these serration behaviours from a perspective of inhomogeneity. The different serration patterns and shear band dynamics could be reasonably understood. The serration pattern of the Fe-based sample suggests that the brittleness of metallic glasses might result from a lower degree of inhomogeneity, and a less tendency of forming shear band intersections. This study might provide new experimental evidences for different micro-structures (or inhomogeneity) and dynamic behaviours in metallic glasses with different plasticity.

Li 4 Ti 5 O 12 heattreated under nitrogen ambient with outstanding rate capabilities

The powders of spinel Li4Ti5O12 were prepared by heat treating the mixture of rutile TiO2 and Li acetate at 800°C for 3 h under a nitrogen atmosphere and, for comparison, under air as well. The powders heated under N2 show a remarkably higher-rate capability and better cycle stability. The discharge capacity of Li4Ti5O12 heated under N2 at 19°C (corresponding to a 3.2-minute total discharge) reached 107mA h g-1, 22mA h g-1 higher than that of Li4Ti5O12 heated under air, which was 85mA h g-1. The former material also shows a much better cycle stability, with no discharge capacity loss after 300 cycles at 6°C or 16.3°C. The results indicate that heat treatment under low-oxygen partial pressure atmosphere such as N2 could significantly improve the high-rate performance of spinel Li4Ti5O12.