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141.
本文由光谱烧孔的发光动力学方程出发,推导了脉冲光烧孔并选通的情况下量子效率的表达式.在77K下测量了以不同功率的560nm脉冲光烧孔并选通的条件下,孔深随烧孔脉冲数目的变化,验证了烧孔的量子效率与选通光强度的关系.在相同的烧孔条件下测量了BaF(Cl,Br):Sm2+与SrF(Cl,Br):Sm2+的孔深随脉冲数目的变化,验证了量子效率与5DJ-7F0跃迁几率的关系. 相似文献
142.
The upconversion luminescence and dynamics in Er^3+ /Yb^3+ codoped nanocrystalline yttria (7-65 nm) are studied under 980-nm pulsed laser excitation, It is found that the red emission of ^4F9/2-^4I15/2 and the green emission of ^2H11/2/^4S3/2 in nanoparticles with lower concentration of Yb^3+ result from a two-photon excitation, In nanocrystals with higher Yb^3+ concentration, the red emissions from a two-photon excitation, while the green emissions from a three-photon excitation, The luminescence dynamics indicates that as the particle size decreases, both the rise and the decay time constants become shorter, As the size decreases to several nanometres, the rise process nearly disappears, suggesting that the upconversion luminescence originates mainly from self-excitation of Er^3+, instead of the energy transfer of Yb^3+→ Er^3+. 相似文献
143.
The influence of polarization variation of a pump beam on the performance of a “bridge” mutually pumped phase conjugator has been investigated. The reflectivity, transmission, and response time were measured for different polarizations and different intensity rations of input beams. From these measured results, the variation behaviors of parameters of fourwave mixing interactions in the crystal are revealed. 相似文献
144.
本文采用最近发展的十维含时波包方法研究了H+CH3D→H2+CH2D反应的模式选择性,计算了反应物CH3D在基态、CH3对称和不对称伸缩振动激发态、CD伸缩振动激发态以及CH3弯曲模式的基频和倍频激发态等6个初始状态下的反应几率. 计算结果表明,在碰撞能0.0∽1.0 eV区间内,激发CH3的任意一种伸缩振动模都能增强反应活性,而CD伸缩振动激发对反应的促进作用不明显. CH3弯曲振动模的基频激发对促进反应活性几乎没有影响,由于CH3对称伸缩振动模的基频与CH3弯曲振动模倍频之间的费米共振作用,CH3弯曲振动模的倍频激发显著增强了反应活性. 相似文献
145.
The effects of Er3+ ion concentration on 2.0-μm emission performance in Ho3+/Tm3+ co-doped Na5Y9F32 single crystal under 800-nm excitation 下载免费PDF全文
Na5Y9F32 single crystals doped with ~0.8-mol% Ho3+,~1-mol% Tm3+,and various Er3+ ion concentrations were prepared by a modified Bridgman method.The effects of Er3+ion concentration on 2.0-μm emission excited by an800-nm laser diode were investigated with the help of their spectroscopic properties.The intensity of 2.0-μm emission reached to maximum when the Er3+ ion concentration was ~1 mol%.The energy transfer mechanisms between Er3+,Ho3+,and Tm3+ ions were identified from the change of the absorption spectra,the emission spectra,and the measured decay curves.The maximum 2.0-μm emission cross section of the Er3+/Ho3+/Tm3+tri-doped Na5Y9F32 single crystal reached 5.26 × 10-21 cm2.The gain cross section spectra were calculated according to the absorption and emission cross section spectra.The cross section for ~2.0-μm emission became a positive gain once the inversion level of population was reached 30%.The energy transfer efficiency was further increased by 11.81% through the incorporation of Er3+ ion into Ho3+/Tm3+ system estimated from the measured lifetimes of Ho3+/Tm3+-and Er3+/Ho3+/Tm3+-doped Na5Y9F32single crystals.The present results illustrated that the Er3+/Ho3+/Tm3+tri-doped Na5Y9F32 single crystals can be used as promising candidate for 2.0-μm laser. 相似文献