Eu3＋ and Ce3＋ co-doped YPO4 microspheres were synthesized by hydrothermal method without template. The emission spectra showed that the red emission centered at 618nm could be readily increased relatively to the ora...Eu3＋ and Ce3＋ co-doped YPO4 microspheres were synthesized by hydrothermal method without template. The emission spectra showed that the red emission centered at 618nm could be readily increased relatively to the orange emission centered at 590nm by controlling the doping concentration of Ce3＋ ion. The investigation based on excitation spectra and decay curves demonstrated that the doped Ce3＋ ions took two efficient energy transfers to Eu3＋ ions and affected the lifetime of the emission states of Eu3＋ ions so that the emission spectra of Eu3＋ ion were accordingly tuned with the Ce3＋ content increasing. This controllable red （5D0→7F2） to orange （ 5D0→7F1） emission ratio of YPO4：Eu3＋,Ce3＋ made it very promising for encoded anti-fake labels and bio-labels.展开更多
It is a long-held tenet of nuclear physics, from the early work of Rutherford and Soddy up to present times that the disintegration of each species of radioactive nuclide occurs randomly at a constant rate unaffected ...It is a long-held tenet of nuclear physics, from the early work of Rutherford and Soddy up to present times that the disintegration of each species of radioactive nuclide occurs randomly at a constant rate unaffected by interactions with the external environment. During the past 15 years or so, reports have been published of some 10 or more unstable nuclides with non-exponential, periodic decay rates claimed to be of geophysical, astrophysical, or cosmological origin. Deviations from standard exponential decay are weak, and the claims are controversial. This paper examines the effects of a periodic decay rate on the statistical distributions of 1) nuclear activity measurements and 2) nuclear lifetime measurements. It is demonstrated that the modifications to these distributions are approximately 100 times more sensitive to non-standard radioactive decay than measurements of the decay curve, power spectrum, or autocorrelation function for corresponding system parameters.展开更多
基金Project supported by National Natural Science Foundation of China(51175172)Natural Science Foundation of Hunan Province(10JJ6008)the Innovation Foundation of Hunan University of Science and Technology(S100126)
文摘Eu3＋ and Ce3＋ co-doped YPO4 microspheres were synthesized by hydrothermal method without template. The emission spectra showed that the red emission centered at 618nm could be readily increased relatively to the orange emission centered at 590nm by controlling the doping concentration of Ce3＋ ion. The investigation based on excitation spectra and decay curves demonstrated that the doped Ce3＋ ions took two efficient energy transfers to Eu3＋ ions and affected the lifetime of the emission states of Eu3＋ ions so that the emission spectra of Eu3＋ ion were accordingly tuned with the Ce3＋ content increasing. This controllable red （5D0→7F2） to orange （ 5D0→7F1） emission ratio of YPO4：Eu3＋,Ce3＋ made it very promising for encoded anti-fake labels and bio-labels.
文摘It is a long-held tenet of nuclear physics, from the early work of Rutherford and Soddy up to present times that the disintegration of each species of radioactive nuclide occurs randomly at a constant rate unaffected by interactions with the external environment. During the past 15 years or so, reports have been published of some 10 or more unstable nuclides with non-exponential, periodic decay rates claimed to be of geophysical, astrophysical, or cosmological origin. Deviations from standard exponential decay are weak, and the claims are controversial. This paper examines the effects of a periodic decay rate on the statistical distributions of 1) nuclear activity measurements and 2) nuclear lifetime measurements. It is demonstrated that the modifications to these distributions are approximately 100 times more sensitive to non-standard radioactive decay than measurements of the decay curve, power spectrum, or autocorrelation function for corresponding system parameters.
