An experimental study of energy transfer collisions,Cs(6P3/2)+ Cs(6P3/2)+He→Cs(4FJ)+Cs(6S1/2)+He,in the range 337 K to 357 K,has carried out in a cell.Atoms were excited to the 6P3/2 state using a single-mode diode laser.The Cs(6P3/2) atom density and spatial distribution were mapped by monitoring the absorbion of a counterpropagating laser beam.The buffer gas enhanced the energy transfer between two 6P3/2,which was based on the measurement of the fluorescence from the 4FJ states populated by three-body collision.The three-body collision rate coefficients(in units of 10-27 cm6s-1) for 4F5/2 and 4F7/2 are 1.35±0.18,2.22±0.21,respectively.
An experimental study of energy transfer collisions,Cs(6P3/2)+ Cs(6P3/2)+He→Cs(4FJ)+Cs(6S1/2)+He,in the range 337 K to 357 K,has carried out in a cell.Atoms were excited to the 6P3/2 state using a single-mode diode laser.The Cs(6P3/2) atom density and spatial distribution were mapped by monitoring the absorbion of a counterpropagating laser beam.The buffer gas enhanced the energy transfer between two 6P3/2,which was based on the measurement of the fluorescence from the 4FJ states populated by three-body collision.The three-body collision rate coefficients(in units of 10-27 cm6s-1) for 4F5/2 and 4F7/2 are 1.35±0.18,2.22±0.21,respectively.
An experimental study of energy transfer collisions,Cs$(6P_3/2)$+ Cs$(6P_3/2$)+He→Cs(nl_J)+Cs$(6S_1/2$)+He where $nl_J$=$8S_1/2,4F_5/2$ or $4F_7/2$,in the range 330K to 340K,been carried out in a cell.Atoms were excited to the $6P_3/2$ state using a single-mode diode laser.The Cs$(6P_3/2$) atom density and spatial distribution were mapped by monitoring the absorbion of a counterpropagating laser beam.The buffer gas enhanced the energy transfer between two $6P_3/2$,which was based on the measurement of the fluorescence from the $nl_J$ states populated by three-body collision.The three-body collision rate coefficients(in units of 10~-27cm~6$s~-1)$ for 8$S_1/2,4F_5/2$ and $4F_7/2$ are 1.80±0.72,1.28±0.51 and 2.23±0.89,respectively.
An experimental study of energy transfer collisions, Cs(6P)+Cs(6S)+He→Cs(5D) + Cs(6S)+He, at thermal energies, was carried out in a cell. Atoms were excited to the 6P3/2 state using a single-mode diode laser. The Cs(6P) atom density and spatial distribution were mapped by monitoring the absorption of a counter-propagating laser beam. The buffer gas enhanced the energy transfer between Cs(6P) and Cs(6S), which was based on the measurement of the fluorescence from the 7D state populated by the Cs(6P)/Cs(5D) collisions. Since the 5D→6P fluorescence(3.0-3.6μm) can not be detected with this experiment, the rate coefficient has been measured relative to the known rate coefficient of the collision (i.e., 6P+5D→6S+7D). The three-body collision rate coefficient [k3 = (2.2±1.1)×10-28cm6s-1] is obtained.
Aim An experimental study into cesium energy pooling collision,Cs(6P3/2)+Cs(6P3/2)→Cs(nLJ=8S1/2,4F5/2,4F7/2)+Cs(6S1/2),has been carried out in a cell.Methods A single mode semiconductor laser is used to excite the 6P3/2 state,the other single mode laser antiparallel to pumping laser is used as absorption line to detect excited atomic intensity and its spatial distribution,with absorption line transiting from 6P3/2 to 8S1/2 and parallel to the movement of pumping laser.The cross section of energy pooling collisions is obtained by the ratio of the excited atomic density to fluorescence intensity of the spectral line.Results The cross sections of 8S1/2,4F5/2 and 4F7/2 are(5.43±1.56)×10-16 cm2,(4.89±1.16)×10-16 cm2 and(6.17±1.60)×10-16 cm2,respectively.Conclusion Compared with other test results,the calculation results are exact.
Using stepwise excitation of the cesium 8S atoms level in Cs vapor,several collisional and radiative processes have been identified from the intensities and spectra of the Cs fluorescence.The 5D state was populated by 8S→7P→5D transitions.In cesium densities 1016-1017?cm-3,the energy pooling collisions 5D+5D→nL+6S(nL=9D,11S,7F are studied.Since the 5D→6P(3.0-3.6 μm) fluorescence could not be detected with this experiment,the EP rate coefficients have been measured relative to the known rate coefficient of the collision,i.e.,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 6P3/2→8S1/2 transition,which could be translated parallel to the pump beam.The excited atom densities are combined with measured fluorescene ratios to determine cross sections for the cesium energy pooling process.The average values(in units of 10-10?cm3s-1) for nL=9D,11S and 7F are 8.4±4.2,7.3±3.6,and 9.7±4.8,respectively.Influence on k11S and k7F of the energy transfer process 11S+6S7F+6S is also dicussed.
By applying the laser absorption and fluorescence method,the cross sections for the fine structure mixing and quenching of the Cs(6P) state,induced by collision with He atoms,have been measured.Cesium atoms were optically excited to the 6P3/2 state.The excited atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single mode laser beam,which was tuned to the 6PJ→8S1/2 transitions.The effective radiative rates were calculated for the 6PJ→6S transitions.The fluorescence intensity I895 of the sensitized 6P1/2→6S1/2 emission was measured as a function of He density in the range 0.5×1018～4×1018cm-3 at constant temperature T=337 K.It was found that the quantity N/I895 exhibited a parabolic dependence on N,confirming that the quenching of the 6PJ states was due to collision with He atoms,not ground state Cs atoms.The coefficients of the second-order polynomial fitted through the measured data yielded the cross sections σ3/2→1/2=(1.46±0.51)×10-19 cm2 and σD=(2.28±0.80)×10-18 cm2 for the 6PJ fine structure mixing and quenching,respectively,due to collision with He atoms.
We report experimentally the measured rate coefficients for the energy pooling (EP) collisions process Cs(5D)+Cs(5D)-gCs(6S)+Cs(nL=9D,11S,7F) in cesium densities of 10^(16)-10^(17) cm^(-3). The 5D state was populated via 8S-g7P-g5D spontaneous emission following two-step pumping 6S-g6P_(3/2)-g8S. Since the 5D-g6P (3.0-3.6 microns) fluorescence could not be detected in this experiment, we carried out a relative measurement for the process 6P+5D-g6S+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)-g9S_(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) cm3/s), respectively. Influence of the energy transfer process 11S+6S-g7F+6S on the rate coefficients k_(11S) and k_(7F) is also discussed.