Energy-pooling collisions in Rb-Cs vapor mixture Rb(5PJ)+Cs(6P3/2) → Rb(5S1/2)+Cs(nlJ'')

Rate coefficients for energy-pooling (EP) collisions Rb(5PJ) + Cs(6P3/2) → Rb(5S1/2) + Cs(nlJ') have been measured.Atoms were excited to Rb(5PJ) and Cs(6P3/2) states using two single-mode diode lasers.To isolate the heteronuclear contribution in the fluorescence spectrum,a double-modulation technique has been adopted.The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam,tuned to Rb(5PJ → 7S1/2) and Cs(6P3/2 →8S1/2) transitions respectively,which could be translated parallelly to the pump beams.The excited atom densities are combined with the measured fluorescence ratios to determine cross sections for the EP processes.It was found that Rb(5P1/2)+Cs(6P3/2) collisions are more efficient than Rb(5P3/2)+Cs(6P3/2)collisions for populating Cs(4F5/2),while the opposite is true for populating Cs(4F7/2).     

Resonant Reaction in Rb-Cs Vapour Mixture Rb（5P1/2） ＋ Cs（6P3/2） → Cs（8S1/2）＋Rb（5S1/2）

We experimentally study energy-pooling collision in the Rb-Cs vapour mixture at low densities in a cell. Atoms are excited to Rb（5P1/2） and Cs（6P3/2） states using two single-mode diode lasers. To isolate the heteronuclear contribution in the fluorescence spectrum, a double-modulation technique is adopted. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to Rb（5P1/2 → 7S1/2） and Cs（6Pa/2 → 8S1/2） transitions, respectively, which could be translated parallel to the pump beams. The excited atom densities are combined with the measured fluorescence ratios to determine cross section for the energy-pooling process [i.e. Rb（5P1/2） ＋Cs （6P3/2） → Cs（8S1/2）＋Rb （5S1/2）]. The cross section is 3.79 × 10^-14 cm^2 ± 45%.     

Energy-Pooling Collisions in Rubidium： 5P3/2 ＋ 5P3/2 → 5S ＋ （nl = 5D, 7S）

We experimentally study rubidium energy pooling collisions of Rb（SP3/2） ＋ Rb（5P3/2） → Rb（5S1/2） ＋ Rb （nlJ = 5DJ, 7S1/2） at low densities in a cell using diode laser excitation. The excited-atom density and spatial distribution are mapped by monitoring the absorption of a counterpropagating single-mode diode laser beam, tuned to the 5P3/2 → 7S1/2 transition, which could be translated parallel to the pump beam. The excited atom densities are combined with measured fluorescence ratios to determine cross sections for the rubidium energy pooling process. The cross sections for nlJ being 5D5/2, 5D3/2, and 7S1/2 are （1.32±0.59）×10^-14, （1.18±0.53）×10^-14 and （3.21±1.44）×10^-15cm^2, respectively.     

Experimental study of cesium 5D 5D→6S (nL=9D,11S,7F)energy pooling collisions

We report experimentally the measured rate coefficients for the energy pooling(EP)collisions process Cs(5D) Cs(5D)→Cs(6S) Cs(nL=9D,11S,7F)in cesium densities of 10~(16)-10~(17)cm~(-3).The 5D state was populated via 8S→7P→5D spontaneous emission following two-step pumping 6S→6P_(3/2)→8S. Since the 5D→6P(3.0—3.6μm)fluorescence could not be detected in this experiment,we carried out a relative measurement for the process 6P 5D→6S 7D.The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode laser beam, tuned to 6P_(3/2)→9S_(1/2)transition,which could be translated parallelly to the pump beam.The excited atom densities have been combined with the measured fluorescence ratios to yield EP rate coefficients. The average values for nL=9D,11S and 7F are 8.0±4.0,7.0±3.5,and 9.3±4.6(in units of 10~(-10) cm~3/s),respectively.Influence of the energy transfer process 11S 6S(?)7F 6S on the rate coefficients k_(11S)and k_(7F)is also discussed.     

Experimental study of cesium 5D + 5D → 6S + (nL = 9D, 11S, 7F) energy pooling collisions

We report experimentally the measured rate coefficients for the energy pooling (EP) collisions process Cs(5D) +Cs(5D) → Cs(6S)+Cs(nL = 9D, 11S, 7F) in cesium densities of 1016 -1017 cm-3 . The 5D state was populated via 8S → 7P → 5D spontaneous emission following two-step pumping 6S → 6P3/2 → 8S.Since the 5D → 6P (3.0-3.6 μm) fluorescence could not be detected in this experiment, we carried out a relative measurement for the process 6P + 5D → 6S + 7D.     

THE 82S1/2→62D EXCITATION TRANSFER OF RUBIDIUM ATOMS INDUCED BY COLLISIONS WITH GROUND-STATE RUBIDIUM AND HYDROGEN MOLECULES

The processes of excitation transfer from the 8²S_1/2 state to the 6²D state of rubidium in Rb(8²S_1/2)-Rb(5²S_1/2) and Rb(8²S_1/2)-H₂ collisions have been studied experimentally. During irradiating the Rb vapor, mixed with H₂, by two light beams for selective stepwise excitation, the Rb 8²S_1/2→5²P_3/2 direct fluorescence and the Rb 6²D_3/2→5²P_1/2 sensitized fluorescence have been measured as a function of H₂ gas pressure. The measurements yielded the cross-sections σ(8²S_1/2→6²D) and σ^*(8²S_1/2→6²D) of Rb 8²S_1/2→6²D excitation tranfer induced by collisions with 5²S_1/2 atom and H₂ molecules respectively. The results are discussed in detail.     

Transition Dipole Moment Measurements of Ultracold Photoassociated ~(85)Rb~(133)Cs Molecules by Depletion Spectroscopy

The transition dipole moments(TDMs) of ultracold85 Rb133 Cs molecules between the lowest vibrational ground level, (X~1Σ~+( v= 0, J= 1), and the two excited rovibrational levels, 2~3Π_0+(v′= 10, J′= 2) and 2~1Π_1(v′= 22,J′= 2), are measured using depletion spectroscopy. The ground-state85 Rb133 Cs molecules are formed from cold mixed component atoms via the 2~3Π_0-( v= 11, J= 0) short-range level, then detected by time-of-flight mass spectrum. A home-made external-cavity diode laser is used as the depletion laser to couple the ground level and the two excited levels. Based on the depletion spectroscopy, the corresponding TDMs are then derived to be 3.5(2)×10~(-3)eα_α and 1.6(1)×10~(-2)eα_α, respectively, where 0)(60 represents the atomic unit of electric dipole moment. The enhance of TDM with nearly a factor of 5 for the 21Π1(v′= 22, J′= 2) excited level means that it has stronger coupling with the ground level. It is meaningful to find more levels with much more strong coupling strength by the represented depletion spectroscopy to realize direct stimulated Raman adiabatic passage transfer from scattering atomic states to deeply molecular states.     

Rb(5PJ)+Rb(5PJ)→Rb(5S)+Rb(nl=5D,7S)碰撞能量合并

研究了Rb(5PJ) Rb(5PJ)→Rb(nlJ') Rb(5S)碰撞能量合并过程,利用单模半导体激光器分别共振激发Rb原子的5P1/2或5P3/2态,利用另一与泵浦激光束反向平行的单模激光束作为吸收线探测激发态原子密度及其空间分布,吸收线分别调至5P1/2→5D3/2和5P3/2→7S1/2跃迁.由激发态原子密度和谱线荧光比得到碰撞能量合并过程的截面,对5P3/2激发,碰撞转移得到5D5/2,5D3/2和7S1/2的截面分别是(1.32士0.59)×10-14,(1.18士0.53)×10-14和(3.21士1.44)×10-15cm2;对5P1/2激发,碰撞转移到5D5/2和5D3/2的截面分别是(6.57士2.96)×10-15和(5.90士2.66)×10-15cm2.与其他的实验结果进行了比较.     

Measuring Transmittance in Rubidium Vapour Cells Using an Extremely Weak Coherent Field of Light

The absorptive properties of the atomic transition in the Rb^85 D2 (A) line (5S1/2-5P3/2) at 780.Onm are measured by using a continuous tunable diode laser and a CCD detector in Rb vapour cell under the condition of extremely weak incident intensity. When the intensity of incident light decreases from 420pW/cm^2 to 0.03pW/cm^2, the transmittance is found to be independent of the incident intensity within our experimental accuracy.     

Rb(5 P_J)+(He、N_2)碰撞能量转移

在气体样品池条件下,研究了Rb(5PJ) (He、N2)碰撞能量转移过程.调频半导体激光器稍微调离共振线,激发Rb原子至Rb(5P3/2)态,在不同的He或N2气压下,测量了直接5P3/2→5S1/2荧光和转移5P1/2→5S1/2荧光.对于5PJ与He的碰撞.电子态能量仅能转移为He原子的平动能.在与N2的碰撞中,向分子振转态的转移是重要的.利用速率方程分析,可以得到碰撞转移速率系数,对于He,5P3/2→5S1/2转移速率系数为2.23×10-12cm3s-1.对于N2,测量5PJ He和5PJ N2二种情况下荧光的相对强度比,利用最小二乘法确定5P3/2→5S1/2转移速率系数为4.38×10-11cm3s-1,5PJ态猝灭速率系数为5.45×10-11cm3s-1.与其他实验结果进行了比较.     

Cs(6DJ)+Cs(6S1/2)非弹性碰撞转移截面的测定

在9×1014～2.1×1015cm-3 Cs密度范围内,利用脉冲激光双光子激发Cs(6S1/2)到Cs(6D5/2)态,使用原子荧光光谱方法,通过三能级模型的速率方程分析,由对直接荧光和转移荧光的时间积分强度的测量,得到6D5/2→6D3/2精细结构转移截面为(2.1±0.4)×10-14cm2,而6D3/2态向6D以外态的转移截面为(1.6±0.4)×10-14cm2,它应是过程Cs(6 D3/2)+Cs(6S)→Cs(6P)+Cs(6P),6D3/2→7P3/2和6D3/2→7 P1/2碰撞转移截面之和.第二个实验可以得到6 D3/2→7P3/2和6D3/2→7 P1/2的碰撞转移截面.在1×1012～6×1012cm-3的低密度Cs蒸气中,激光双光子激发6S至6D3/2或6D5/2态,测量6DJ→6PJ'与7PJ"→6S1/2的时间积分荧光强度比,得到6D3/2→7P1/2与6D5/2→7R3/2的碰撞转移截面分别为(7.6±2.4)×10-15cm2与(1.6±0.5)×10-15cm2.由此得到碰撞能量合并的逆过程即[Cs(6D3/2)+Cs(6S1/2)→Cs(6P)+Cs(6P)]的转移截面为(1.3±0.4)×10-14cm2.     

Cs(6P)激发态的辐射及与N2碰撞的能量转移

应用激光吸收和荧光方法,测量了Cs(6P)态与N2碰撞的精细结构转移和碰撞猝灭截面。Cs原子被激光激发到6P3/2态,将与泵浦激光束反向平行的检测激光束调到6PJ→8S1/2的跃迁,测量了6PJ激发态的密度及空间分布,由此计算了6PJ→6S的有效辐射率。在T=337 K(蒸气压公式给出Cs密度N0=1.25×1012cm-3)和N2密度2×1016相似文献   

Rb蒸气中的5PJ+5PJ′→5S+5DJ″碰撞能量合并

研究了Rb(5PJ) Rb(5PJ′)→Rb(5S) Rb(5DJ″)的碰撞能量合并过程,一台单模半导体激光器共振激发Rb原子的5P1/2或5P3/2态,另一与泵浦激光束反向平行的单模激光束作为吸收线探测激发态原子密度及其空间分布,吸收线分别调至5P1/2→5D3/2和5P3/2→7S1/2跃迁,由激发态原子密度和谱线荧光比得到碰撞能量合并过程5PJ 5PJ′→5S 5DJ″的截面.两台激光器同时分别激发5P1/2和5P3/2态,通过对5DJ″→5PJ的荧光探测,得到5P3/2 5P1/2碰撞转移到5D5/2和5D3/2的截面分别为(1.12±0.50)×10-14和(1.01±0.45)×10-14cm2.     

Experimental evaluation of rate coefficients for Rb（5Dj）＋H2→ RbH＋H reaction

The Rb（5Dj）＋H2→RbH＋H photochemical reaction has been studied. Rb vapor mixed with H2 is irradiated in a glass cell with 778-nm pulses which populate one of the 52D states by two-photon absorption. Measurements for the relative intensities of the atomic fluorescence and the absorption of the RbH product near the axis of the cell yield the rate coefficients for the Rb（5D3/2）＋H2 and Rb（5D5/2）＋H2 reactions, which are （3.6±1.3） ×10^-11 and （1.7±0.6）×10^-11 cm^3/s, respectively. The relative reactivity with H2 for Rb（5D3/2） is higher than that for Rb（5D5/2）.     

Infrared quantum cutting conversion luminescence of Tb(0.7)Yb(3):FOV

The infrared quantum cutting of oxyfluoride nanophase vitroceramics Tb(0.7)Yb(3):FOV has been studied in the present paper. The actual quantum cutting efficiency formula calculated from integral fluorescence intensity is extended to the case of Tb(0.7)Yb(3):FOV. The visible and the infrared fluorescence spectra and their integral fluorescence intensities are measured from static fluorescence experiment. Lifetime curve is measured from dynamic fluorescence experiment. It is found that the total actual quantum cutting efficiency η of the excited ⁵D₄ level is about 93.7%, and that of excited (⁵D₃, ⁵G₆) levels is 93.5%. It is also found that the total theoretical quantum cutting efficiency upper limit η_x%Yb of the 485.5 nm excited <⁵D₄ level is about 121.7%, and that of 378.5 nm excited (⁵D₃, ⁵G₆) levels is 137.2%.     

Laser 728 nm Spectroscopy of Electrodeless Discharge Rb Lamp

The electrodeless discharge rubidium vapor lamp plays a key role in a number of applications, such as atomic clock, atomic magnetometer, atomic optical filter and laser frequency stabilization. The electrodeless discharge Rb vapor lamp has rich spectra, including 420nm, 421nm, 565nm, 572nm, 607nm, 616nm, 728 nm, 776 nm, 780 nm, 795 nm, 1324 nm, 1344 nm, 1366 nm, 1475 nm, 1529 nm spectroscopy, etc. The 780nm transition wavelength between 5P3/2 and 5S1/2 of Rb atoms is usually used in fields of the Rb atomic clock and the Rb atomic magnetometer.With the 421.7 nm laser pumping atoms from 5S1/2 to 6P1/2, 1366.9 nm transition from 6S1/2 to 5P3/2 can be used as a clock transition of Rb four levels for an atomic active optical clock. An active optical clock is a new conception of the atomic clock and has the potential to improve the stabil- ity of the best atomic clocks by about two orders of magnitude. Another application of the elec- trodeless discharge Rb vapor lamp is the Rb Faraday anomalous-dispersion optical filter （FADOF） （e.g., 776 nm] and 1529 nm spectroscopy）, in which the electrodeless discharge Rb vapor lamp is more feasible than the one using a laser pumped Rb vapor cell in some cases, since many excited states are populated enough for aimed FADOF transition. Although the rich spectra of Rb have many applications, so far no detailed investigations or applications have been achieved in 728.0nm transition. To the best of our knowledge, the Rb 728.0 nm spectral data are currently only from the fluorescence by Beacham arc spectrum of rubidium early in 1959.     

THE 82S1/2→62D EXCITATION TRANSFER OF RUBIDIUM ATOMS INDUCED BY COLLISIONS WITH GROUND-STATE RUBIDIUM AND HYDROGEN MOLECULES

The processes of excitation transfer from the 8²S_1/2 state to the 6²D state of rubidium in Rb(8²S_1/2)-Rb(5²S_1/2) and Rb(8²S_1/2)-H₂ collisions have been studied experimentally. During irradiating the Rb vapor, mixed with H₂, by two light beams for selective stepwise excitation, the Rb 8²S_1/2→5²P_3/2 direct fluorescence and the Rb 6²D_3/2→5²P_1/2 sensitized fluorescence have been measured as a function of H₂ gas pressure. The measurements yielded the cross-sections σ(8²S_1/2→6²D) and σ^*(8²S_1/2→6²D) of Rb 8²S_1/2→6²D excitation tranfer induced by collisions with 5²S_1/2 atom and H₂ molecules respectively. The results are discussed in detail.     

THE 82S1/2→62D EXCITATION TRANSFER OF RUBIDIUM ATOMS INDUCED BY COLLISIONS WITH GROUND-STATE RUBIDIUM AND HYDROGEN MOLECULES

The processes of excitation transfer from the 8²S_1/2 state to the 6²D state of rubidium in Rb(8²S_1/2)-Rb(5²S_1/2) and Rb(8²S_1/2)-H₂ collisions have been studied experimentally. During irradiating the Rb vapor, mixed with H₂, by two light beams for selective stepwise excitation, the Rb 8²S_1/2→5²P_3/2 direct fluorescence and the Rb 6²D_3/2→5²P_1/2 sensitized fluorescence have been measured as a function of H₂ gas pressure. The measurements yielded the cross-sections σ(8²S_1/2→6²D) and σ^*(8²S_1/2→6²D) of Rb 8²S_1/2→6²D excitation tranfer induced by collisions with 5²S_1/2 atom and H₂ molecules respectively. The results are discussed in detail.     

Rotational and Vibrational State Distributions of CsH and Relative Reactivity in Reactions of Cs（6^2D,7^2D） with H2

By using a pump-probe technique, the nascent rotational and vibrational state distributions of CsH are obtained in the Cs（6^2 D,7^2 D） plus H2 reaction. The nascent CsH molecules are found to populate the lowest two vibrational （v″ = 0 and 1） levels of the ground electronic state. By comparing the spectral intensities of the CsH action spectra with those of pertinent Cs atomic fluorescence excitation spectra, the relative reactivity with 1-12 is in an order of6^2D3/2 〉 6^2D5/2 〉 7^2D3/2 〉 7^2D5/2. The rotational temperatures are found to be slightly below the cell temperature. The relative fractions （〈fV〉, 〈fR〉, 〈fT〉） of average energy disposal are derived as （0.2,0.12,0.68）, （0.2,0.12,0.68）, （0.07,0.04,0.89） and （0.07,0.04,0.89） for the 6^2D3/2, 6^2D5/2, 7^2D3/2 and 7^2D5/2, respectively. The major available energy is released as translation. These results support that the reaction mechanism of Cs（6^2 D,7^2 D） plus 112 is primarily a eollinear abstraction and not an insertion.     

金核-金核与质子-质子对撞中矢量介子K*0(892)和φ(1020)的自旋排列

We present the preliminary results on the spin alignment matrix elementρ_(00)for vector mesons K~(*0)(892)andφ(1020)in mid-central(20%—60%)Au Au and p p collisions at S_(NN)~(1/2)=200GeV.The values ofρ_(00)with respect to reaction plane in Au Au collisions are 0.36±0.02(stat)±0.13(sys)for K~(*0)(892)and 0.38±0.01(stat)±0.04(sys)forφ(1020).No evident global spin alignment with respect to reaction plane is observed in the measured p_T region up to 5GeV/c with current sensitivity,ρ_(00)with respect to the production plane of the vector meson is also measured for K~(*0)(892)andφ(1020)in Au Au collisions,and forφ(1020)in p p collisions.No significant difference for theρ_(00)between Au Au and p p collisions is observed with our data sample.