Die Hyperfeinstruktur des 6s 6p 3 P 1-Zustandes von171Yb und173Yb

The hyperfine structure of the 6s 6p ³ P ₁ state of¹⁷¹Yb and¹⁷³Yb has been investigated by the level crossing technique and by optical double resonance. The following results for the magnetic hfs splitting constantA and for the electric quadrupole interaction constantB have been obtained:A(¹⁷¹Yb)=3959.1(14)Mc/sec;A(¹⁷³Yb)=?1094.7(6) Mc/sec;B(¹⁷³Yb)=?826.9(9) Mc/sec. The hyperfine structure anomaly of the isotopes¹⁷¹Yb and¹⁷³Yb was determined to beΔ=?0.36(3)%.     

Doppelresonanzexperimente zur Untersuchung der Hyperfeinstruktur des 6s6p 3 P 1-Zustandes von171Yb und173Yb

For the odd Yb isotopes¹⁷¹Yb and¹⁷³Yb the hyperfine splitting of the 6s6p ³ P ₁ state has been measured by optical double resonance in zero magnetic field. Taking into account second order corrections due to the influence of the 6¹ P ₁ and 6³ P _0,2 states, the following results for the magnetic splitting constantA and the electric quadrupole interaction constantB have been derived: A(¹⁷¹Yb)=3958.228 (60) Mc/s, A(¹⁷³Yb)=?1094.318 (35) Mc/s, S(¹⁷³Yb)=?825.904 (85) Mc/s. The hyperfine structure anomaly of the isotopes¹⁷¹Yb and^{171 173}Yb was determined to be Δ=?0.352 (10)%.     

Die isomeren Atomkerne: Yb169m,Yb175m,Yb177m

Short lived isomers of Yb were produced by neutron irradiation of enriched isotopes and have been investigated with the aid of scintillation spectrometers. Yb^169m decays with a half-life ofT _1/2=(46±2) sec emitting only L-radiation. This decay is assumed to be the same as the E 3-transition of 24 keV following the electron capture of Lu¹⁶⁹. Yb^175m [T _1/2=(0,072±0,005) sec] emitsγ-rays of (495±15) keV. The measured K-conversion coefficientα _{K 495}=0,24±0,04 and the total conversion coefficientα _{4 5}=0,6±0,3 indicate the transition to be M3. Yb^177m [T _1/2=(6,4±0,1) sec] decays by a cascade of twoγ-rays. The isomeric (228±3) keV-transition is followed by a (104±1,5) keV-radiation. The measured conversion coefficients areα _{K 228}=4,1±0,4 andα _{K 228}=6,5±0,5 for the first transition andα _{K 104}=0,39±0,05 andα ₁₀₄=0,51±0,05 for the second, indicating a M3-E1-cascade. For the M 3-transition the measured coefficients agree well with those calculated for a nucleus of finite size, but they differ by a factor of 1,5 for the E1-transition.     

CW laser performance of Yb and Er,Yb doped tungstates

 Room temperature cw laser action of Yb³⁺-doped KY(WO₄)₂ and KGd(WO₄)₂ crystals at 1.025 μm and Er, Yb : KY(WO₄)₂ at 1.54 μm has been demonstrated under pumping by both Ti-sapphire laser and InGaAs laser diodes. A slope efficiency of Yb-lasers up to 78% has been obtained. Received: 19 June 1996     

Continuous wave diode pumped Yb:LLF and Yb:NYF lasers

Experimental and theoretical results of investigation of CW Yb:LiLuF₄ (Yb:LLF) and Yb:Na₄Y₆F₂₂ (Yb:NYF) lasers under longitudinal diode laser pump are reported. Slope efficiencies of 41%, 58% with 0.21, 0.53 W of output powers were obtained for the Yb:LLF and Yb:NYF lasers, correspondingly. The Yb:NYF laser demonstrated tunability in the region from 1005 to 1061 nm. The mathematical modelling of CW laser operation predicts under optimized laser parameters optical to optical efficiencies of about 55% and 51% for Yb:LLF and Yb:NYF lasers, respectively.     

Bestimmung der Kerndipolmomente von171Yb und173Yb durch optisches Pumpen

The nuclear Zeeman levels of the odd isotopes of Ytterbium (¹⁷¹Yb,¹⁷¹ I=1/2;¹⁷³Yb,¹⁷³ I=5/2) were polarized in the atomic ground state (6s ^{2 1} S ₀) by means of optical pumping with the resonance line (6s ^{2 1} S ₀ ? 6s6p ¹ P ₁,λ=3988 å). The magnetic moments, calculated from the nuclear Hf-Zeeman transitions in a magnetic field of 228 Gauss are¹⁷¹ Μ _I=0.49188 (2)Μ _K ¹⁷³ Μ _I=0,67755 (3)Μ _K (with diamagnetic correction applied).     

Side-bands in170Yb

The energy spectra of the even-parity (K ^π = 2⁺, 3⁺) and odd-parity (K ^π = 3⁻, 4⁻) side-bands in the doubly even nucleus¹⁷⁰Yb are studied in the framework of the microscopic method of variation after angular momentum projection with nucleon number conservation in each projected state. The calculated energy spectra of the ground band and the four side bands in¹⁷⁰Yb are in good agreement with the corresponding experimental results.     

Yb:YAG及Cr,Yb:YAG晶体的发光特性

研究了室温下YbYAG的上转换荧光光谱,此荧光归因于Yb3+离子的"合作"发光和Yb3+离子到稀土杂质离子的能量转移.测试了YbYAG晶体的X射线荧光,发光峰对应于电荷迁移态到Yb3+离子的基态、激光态间的跃迁.研究了Cr,YbYAG晶体的荧光光谱,讨论了Cr4+激光输出的可能性.     

Comparison of spectroscopic properties of Yb:YAP and Yb:YAG crystals

The Yb:YAG and Yb:YAP crystals have been grown by Czochralski method. The absorption spectra and the fluorescence spectra of Yb:YAG and Yb:YAP crystals have been investigated. It is shown that the Yb:YAG crystal has better laser properties and smaller threshold power than Yb:YAP crystal. In addition, the absorption cross-section of the Yb:YAP crystal is 2.16 times of that of the Yb:YAG crystal,so laser diode pumped Yb:YAG lasing can be easily realized. Because YAP single crystal is anisotropic, it is provided with polarization characteristics.     

Characterization of quasiparticle states at and beyond stability in ytterbium isotopes: Spectroscopy of 175Yb, 176Yb and 177Yb

Excited states in ¹⁷⁵Yb, ¹⁷⁶Yb and ¹⁷⁷Yb were populated via the bombardment of a ¹⁷⁶Yb target with a 750 MeV ¹³⁶Xe beam. Gamma-ray decays from these states were measured with the AFRODITE multi-detector spectrometer. The rotational band previously assigned to the ground state of ¹⁷⁷Yb has been reassigned to the first-excited state of ¹⁷⁵Yb. A new rotational band based on the ground state of ¹⁷⁷Yb is presented, and the band based on the K^π = 4^- two-quasiparticle state in ¹⁷⁶Yb has been identified. Also a candidate for the rotational band based on the K^π = 8^-, T_1/2 = 11.4(3) s two-quasiparticle state in ¹⁷⁶Yb has been found. Comparisons of g_K values derived from in-band branching ratios are consistent with the ν9/2⁺[624] assignment to the ground state of ¹⁷⁷Yb, the ν²{9/2⁺[624] ⊗ 1/2^-[510]} assignment to the K^π = 4^- state and with the ν²{9/2⁺[624] ⊗ 7/2^-[514]} assignment to the K^π = 8^- metastable excited state in ¹⁷⁶Yb.     

Additive colouring of CaF2:Yb crystals: determination of Yb2+ concentration in CaF2:Yb crystals and ceramics

When growing CaF₂ crystal doped with rare-earth ions, most of these ions are present in a trivalent state. However, due to contact with graphite crucible, a small proportion of a number of ions (Eu, Sm, Yb and Tm) are reduced to a bivalent state. A similar situation takes place during fabrication of CaF₂ ceramics doped with rare-earth metals. This fact is of particular importance for laser CaF₂:Yb crystals (ceramics), a promising material for short-pulse, high-power, high-energy diode-pumped solid state lasers since the presence of bivalent Yb ions can be a source of thermal losses. To date, there has been no technique to determine Yb²⁺ concentration in as-grown crystals. The proposed technique is based on a total reduction of Yb³⁺ ions via the heating of as-grown CaF₂ crystals with known concentration of Yb in the reducing atmosphere of metal vapour and determining the cross section of absorption bands of Yb²⁺ ions. The knowledge of these parameters allows estimation of the Yb²⁺ content in CaF₂:Yb crystals or ceramics by analysing their absorption spectra. Examples of using this technique are given. The technology of CdF₂ crystals reduction (an “additive colouring”) and features of colouring of crystals doped with rare-earth ions are considered.     

Yb :YAG晶体的闪烁特性

通过不同Yb³⁺掺杂浓度(5%~30%,原子数分数)的Yb:YAG晶体的阴极射线发光谱、衰减时间、光输出及其温度依赖关系的测量,研究了Yb:YAG晶体的闪烁性能.不同Yb³⁺掺杂浓度的Yb:YAG晶体具有不同的光输出和猝灭温度,光输出随Yb³⁺掺杂浓度的增大而降低,猝灭温度则随掺杂浓度的增大而升高.室温下Yb:YAG晶体的发光衰减时间较短,均小于50ns.Yb³⁺掺杂浓度为5%的Yb:YAG晶体具有较高的光输出和较低的猝灭温度.     

Study of159Yb decay

Theβ ⁺-decay of 1.4 min¹⁵⁹Yb was studied at the YAS-NAPP-2 facility installed on the proton beam of the JINR Dubna phasotron. The singles γ-ray spectra and prompt and delayedγ-γ coincidences were measured on the multidetector system. The decay scheme of¹⁵⁹Yb was proposed on the basis of theγ-γ coincidence data. The low lying states of¹⁵⁹Tm were preliminary identified within the framework of the rotational model.     

157Yb的形状共存研究

利用在束γ谱学方法,通过反应¹⁴⁴Sm(¹⁶O,3n)¹⁵⁷Yb研究了¹⁵⁷Yb的激发态能级结构.实验中使用的¹⁶O束流能量为90MeV.基于实验得到的γγ符合关系、γ射线的各向异性度和DCO系数,建议了¹⁵⁷Yb的高自旋能级纲图.¹⁵⁷Yb的能级纲图主要由两串跃迁性质明显不同的级联能级组成,它们分别对应于νi_13/2转动带和单粒子激发态.着重讨论了¹⁵⁷Yb的形状共存和νi_13/2转动带随角动量的结构演化.     

锁模Yb：S—FAP激光器

本文首次报道了连续波Ｔｉ：Ｓａｐｐｈｉｒｅ纵向泵浦主动锁模Ｙｂ：Ｓ－ＦＡＰ激光器。实验得的最短锁模脉宽为３５．４ｐｓ，通过特殊设计的定态激发光谱实验，我们对它的锁模特性进行了研究，因为从理论上说Ｙｂ：ＹＳ－ＦＡＰ４ｎｍ的荧光线宽应能得到更短的变换极限脉宽。     

角抽运Yb:YAG激光器

报道了一种高功率准三能级激光器角抽运方法，抽运光从板条激光器结构中的板条工作介质的角注入，综合考虑抽运吸收、抽运亮度、晶体的掺杂浓度以及晶体尺寸等因素，进行了角抽运复合Yb:YAG激光器设计，实验上获得了最大连续输出功率400W, 斜效率28%的输出，实验结果充分证明了角抽运原理的正确性和应用于高功率激光器方面的可行性. 关键词： Yb:YAG 角抽运 复合晶体