Thermal energy pooling collisions in cesium vapor: Cs(6P3/2) + Cs(6P3/2) ->Cs(7P3/2,1/2) + Cs(6S1/2)

Z. J. Jabbour, R. K. Namiotka, John Huennekens +3 more

We report experimental rate coefficients for the energy-pooling collisions Cs(6${\mathit{P}}_{1/2}$)+Cs(6${\mathit{P}}_{1/2}$)\ensuremath{\rightarrow}Cs(6${\mathit{S}}_{1/2}$)+Cs(${\mathit{nl}}_{\mathit{J}\ensuremath{'}}$) and Cs(6${\mathit{P}}_{3/2}$)+Cs(6${\mathit{P}}_{3/2}$)\ensuremath{\rightarrow}Cs(6${\mathit{S}}_{1/2}$)+Cs(${\mathit{nl}}_{\mathit{J}\ensuremath{'}}$) where ${\mathit{nl}}_{\mathit{J}\ensuremath{'}}$=7${\mathit{P}}_{1/2}$, 7${\mathit{P}}_{3/2}$, 6${\mathit{D}}_{3/2}$, 6${\mathit{D}}_{5/2}$, 8${\mathit{S}}_{1/2}$, 4${\mathit{F}}_{5/2}$, or 4${\mathit{F}}_{7/2}$. Atoms were excited to either the 6${\mathit{P}}_{1/2}$ or 6${\mathit{P}}_{3/2}$ state using a single-mode Ti:sapphire laser. The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode ring dye laser beam, tuned to either the 6${\mathit{P}}_{1/2}$\ensuremath{\rightarrow}8${\mathit{S}}_{1/2}$ or 6${\mathit{P}}_{3/2}$\ensuremath{\rightarrow}7${\mathit{D}}_{3/2,5/2}$ transitions, which could be translated parallel to the pump beam. Transmission factors, which describe the average probability that photons emitted within the fluorescence detection region can pass through the optically thick vapor without being absorbed, were calculated for all relevant transitions. Effective lifetimes of levels populated by energy-pooling collisions are modified by radiation trapping, and these factors were calculated using the Molisch theory. These calculated quantities have been combined with the measured excited-atom densities and fluorescence ratios to yield absolute energy-pooling rate coefficients. It was found that the rate for production, in all cases, is greatest for 6D, but that 1/2-1/2 collisions are significantly more efficient than 3/2-3/2 collisions for populating 7P. It was also found that 7${\mathit{P}}_{1/2}$ is populated two to three times more efficiently than 7${\mathit{P}}_{3/2}$ in 1/2-1/2 collisions, but that the 7P fine-structure levels are approximately equally populated in 3/2-3/2 collisions. \textcopyright{} 1996 The American Physical Society.

Qian Wang, Yifan Shen, Kang Dai

M. Allegrini, F. De Tomasi, Slobodan Milošević +1 more

Two experiments on cesium vapor at relative low number densities (≊1010÷1013 cm−3), excited at the first resonance transition 6S1/2→6P3/2 (λ=852 nm) by a cw laser diode are reported. We have measured the rate coefficients at thermal energies for the energy pooling to the 7P levels. In presence of Ne as buffer gas we have observed a striking distortion of the line‐shape.

Zeina J. Kubarych, Slobodan Milošević, A Allegrini +2 more

Cedomil Vadla

Wen-Yi Huang, Baodong Yang, Fan Jian +2 more

We demonstrate the generation of coherent and collimated blue light (CBL) based on cesium (Cs) 6S1/2(F = 4)→6P3/2(F' = 5)→6D5/2(F'' = 6)→7P3/2(F' = 5)→6S1/2(F = 4) diamond-type atomic system in a heated vapor cell. Two infrared pumping lasers with wavelengths at 852 nm (6S1/2→6P3/2) and 917 nm (6P3/2→6D5/2), provide step-wise excitation to the 6D5/2 excited state, and induce strong two-photon coherence between the 6S1/2 state and 6D5/2 state. The atoms undergo a double cascade accompanied with the amplified spontaneous emission at 15.1 μm via the 7P3/2 intermediate excited state, and produce a beam of 455 nm (7P3/2→6S1/2) CBL with highly spatiotemporal coherence through a parametric four-wave mixing process. We investigate the influence of experimental parameters such as polarization combination of the two pumping lasers, and their power, and the temperature of Cs vapor cell on the CBL. Especially, we add a beam of 894 nm laser operating at the 6S1/2(F = 3) →6P1/2 transition as repumping laser, which can pump atoms back to the 6S1/2(F = 4) state from the 6S1/2(F = 3) state, thus significantly improving the power of CBL. This technique of the CBL enhancement via optical pumping is also useful for the other alkali metal atoms.