Based on a theoretical model of Q-switched laser with the influences of the driving signal sent to the Pockels cell and the doping concentration of the gain medium taken into account,a method of achieving high energy ...Based on a theoretical model of Q-switched laser with the influences of the driving signal sent to the Pockels cell and the doping concentration of the gain medium taken into account,a method of achieving high energy sub-nanosecond Q-switched lasers is proposed and verified in experiment.When a Nd:YVO4 crystal with a doping concentration of 0.7 at.%is used as a gain medium and a driving signal with the optimal high-level voltage is applied to the Pockels cell,a stable single-transverse-mode electro-optical Q-switched laser with a pulse width of 0.77 ns and a pulse energy of 1.04 mJ operating at the pulse repetition frequency of 1 kHz is achieved.The precise tuning of the pulse width is also demonstrated.展开更多
Two novel pyran annulated heterocyclic compounds （1 and 2） were synthesized and characterized via IR, lH NMR and H RMS. The structure of compound 1 was verified by single-crystal X-ray diffraction. The in vitro anti...Two novel pyran annulated heterocyclic compounds （1 and 2） were synthesized and characterized via IR, lH NMR and H RMS. The structure of compound 1 was verified by single-crystal X-ray diffraction. The in vitro antibacterial activities of the two compounds against Staphylococcus aureus （S. aureus ATCC 29213）, methicillin-resistant S. aureus （MRSA XJ 75302）, vancomycin-intermediate S. aureus （Mu50 ATCC 700699）, and USA 300 （Los Angeles County clone, LAC） were evaluated by observing the minimum inhibitory concentration.展开更多
YbF（2.357, YbF3, Ba2 YbF7, and Ba 2 upconversion nanocrystals doped with emitter Er^3＋ ion were synthesized in the same solvent system just with changing the molar ratio of Ba^2＋ to Yb^3＋ in the precursor, which c...YbF（2.357, YbF3, Ba2 YbF7, and Ba 2 upconversion nanocrystals doped with emitter Er^3＋ ion were synthesized in the same solvent system just with changing the molar ratio of Ba^2＋ to Yb^3＋ in the precursor, which corresponed to the crystal phases of rhombohedral, orthorhombic, tetragonal, and cubic, respectively. All the samples emitted both 660 nm red light and 543/523 nm green light which originated from Er^3＋-4f^n electronic transitions ~4F（9/2-~4I（15/2 and ~4S（3/2/~2H（11/2-~4I（15/2, respectively. It was worth mentioning that YbF 3：Er^3＋, Ba2 YbF7：Er^3＋, and BaF2：Er^3＋ could emit dazzlingly bright light even under the excitation of a 980 nm CW laser with output power of 0.1 W. Upconversion emission mechanism analysis indicated that the intensity ratio of red to green light highly depended on the synergistic effect of crystal structure, concentration quenching, and particle size, but were not sensitive to crystallinity as previously reported for NaL nF4（Ln=lanthanide.展开更多
基金the National Key Research and Development Program of China(Grant No.2017YFB0405203)the Shanxi“1331 Project”Key Subjects Construction,China(Grant No.1331KSC).
文摘Based on a theoretical model of Q-switched laser with the influences of the driving signal sent to the Pockels cell and the doping concentration of the gain medium taken into account,a method of achieving high energy sub-nanosecond Q-switched lasers is proposed and verified in experiment.When a Nd:YVO4 crystal with a doping concentration of 0.7 at.%is used as a gain medium and a driving signal with the optimal high-level voltage is applied to the Pockels cell,a stable single-transverse-mode electro-optical Q-switched laser with a pulse width of 0.77 ns and a pulse energy of 1.04 mJ operating at the pulse repetition frequency of 1 kHz is achieved.The precise tuning of the pulse width is also demonstrated.
基金supported by the Innovation plan of science and technology of Shaanxi Province(2014KTCL03-03)
文摘Two novel pyran annulated heterocyclic compounds （1 and 2） were synthesized and characterized via IR, lH NMR and H RMS. The structure of compound 1 was verified by single-crystal X-ray diffraction. The in vitro antibacterial activities of the two compounds against Staphylococcus aureus （S. aureus ATCC 29213）, methicillin-resistant S. aureus （MRSA XJ 75302）, vancomycin-intermediate S. aureus （Mu50 ATCC 700699）, and USA 300 （Los Angeles County clone, LAC） were evaluated by observing the minimum inhibitory concentration.
基金Project supported by the National Natural Science Foundation of China(11274263,21301058,11274263)
文摘YbF（2.357, YbF3, Ba2 YbF7, and Ba 2 upconversion nanocrystals doped with emitter Er^3＋ ion were synthesized in the same solvent system just with changing the molar ratio of Ba^2＋ to Yb^3＋ in the precursor, which corresponed to the crystal phases of rhombohedral, orthorhombic, tetragonal, and cubic, respectively. All the samples emitted both 660 nm red light and 543/523 nm green light which originated from Er^3＋-4f^n electronic transitions ~4F（9/2-~4I（15/2 and ~4S（3/2/~2H（11/2-~4I（15/2, respectively. It was worth mentioning that YbF 3：Er^3＋, Ba2 YbF7：Er^3＋, and BaF2：Er^3＋ could emit dazzlingly bright light even under the excitation of a 980 nm CW laser with output power of 0.1 W. Upconversion emission mechanism analysis indicated that the intensity ratio of red to green light highly depended on the synergistic effect of crystal structure, concentration quenching, and particle size, but were not sensitive to crystallinity as previously reported for NaL nF4（Ln=lanthanide.
