An experimental study of rubidium energy pooling collisions, Rb(5P(J)) + Rb(5P(J))-->Rb(nlJ') + Rb(5S), at thermal energies, was carried out in a cell. Atoms were excited to either the 5P 1/2 or 5P 3/2 state using a single-mode diode laser. The excited atom density and spatial distribution were mapped by monitoring the absorption of a counter-propagating single-mode diode laser beam, tuned to either 5P 1/2-->5D 3/2 or 5P 3/2-->7S 1/2 transition, which could be translated parallel to the pump beam. The excited atom densities were combined with the measured fluorescence ratios to determine cross sections for the rubidium energy pooling process. For 5P 3/2 excitation the cross sections for nlJ' being 5D 5/2, 5D 3/2, and 7S 1/2 are (1.32+/-0.59) x 10(-14), (1.18+/-0.53) x 10(-14) and (3. 21+/-1. 44) x 10(-15) cm2, respectively. For 5P 1/2 excitation the cross sections for nlJ' being 5D 5/2 and 5D 3/2 are (6.57+/-2.96) x 10(-15), and (5.90+/-2.66) x 10(-15) cm2, respectively. The results were compared with those of other experiments.
Rb vapor was irradiated in a glass fluorescence cell with pulses of radiation from a YAG laserpumped OPO laser,populating 5D_j(or 7S) state by two-photon absorption.Energy transfer in Rb (5D_J,7S)+Rb(5S) collision is studied using methods of atomic fluorescence.The resulting fluorescence includes a direct component emitted in the optically excited state decay and a sensitized component arsing. from the collisional populated state.At the different densities of the components,fitting a three-state rate equation model,the cross sectionσ=(3.7±0.9)×10~(-14) cm~2 was obtained for Rb(5D_(5/2))→Rb(5D_(3/2)) transfer.The cross section for excitation transfer out of the 5D_J doublet are(3.1±1.2)×10~(-14) cm~2(for J = 5/2) and(2.0±0.6)×10~(-14) cm~2(for J = 3/2),respectively.The energy transfer cross section for the Rb(5D)→Rb(7S) is small,(1.6±0.4)×10~(-16) cm~2.The 5D_J state is quenched mainly in the reverse energy pooling processes,i.e.Rb(5D_J)+Rb(5S)→Rb(5P)+ Rb(5P).
In a vapor cell, the relative intensities of a sensitized fluorescence I3/21 and a direct fluorescence I3/22, as a function of T (100 to 200℃), had been measured by the methods of selective stepwise excitations with a Rb lamp and a tunable CW dye laser. From these measurements, the fine-structure transition cross-section in the 7 2D states of Rb induced in collidsion with ground-state Rb atoms were determined to be σfs (7 2D5/2→72D3/2) = 4.7 × 10-13 cm2 and σfs1 (7 2D3/2→7 2D5/2) = 7.0 × 10-13cm2 and the cross-section for transfer of excited Rb 7 2D-state atoms out of the doublet were
also determined as σtr(5/2) (7 2D5/2→states other than Rb 7 2D) = 0.62 × 10-13 cm2. The calculcted result for the geometrical cross-section of excited Rb 7 2D state shows that the magnitunes of σfs and σfs1 can be described relatively well by σgeom.
Cross sections for inelastic transfer between the 82D3/2 and 82D5/2 fine-structure states in rubidium, induced in resonant collisions with ground-state Rb atoms, have been determined using an experimental method involving two-photon excitation of atomic fluorescence. Rubidium vapor in a fluorescence cell was irradiated with pulses of 641 nm radiation from a N2 laser-pumped dye-laser tuned to excite one of the 82D states. The resulting fluorescence included the direct component originating from the optically excited state and a sensitized component arising from the other fine-structure state populated by collisions. Relative intensities of the fluorescent components, determined by photon-counting techniques, yielded the cross sections for excitation transfer: Q(2D3/2 → 2D5/2) = 8.1 × 10−13 cm2; Q(2D3/2 ← 2D5/2) = 5.5 × 1013 cm2; as well as [Formula: see text], the effective quenching cross section. The excitation transfer cross sections which are considered accurate to within ±20% are in the ratio predicted by the principle of detailed balancing.
Cross sections for $7^{2}D_{\frac{3}{2}}\ensuremath{\leftrightarrow}7^{2}D_{\frac{5}{2}}$ transfer in Rb, induced in collisions with He, Ne, Ar, and with ground-state Rb atoms, have been determined using methods of atomic fluorescence. Rb vapor, pure or mixed with a noble gas, was irradiated in a glass fluorescence cell with pulses of 660-nm radiation from a
N2-laser-pumped dye laser, populating one of the
2D states by two-photon absorption. The resulting fluorescence included a direct component emitted in the decay of the optically excited state and a sensitized component arising from the collisionally populated state. Relative intensities of the components yielded the cross sections for
72D mixing: $Q(^{2}D_{\frac{3}{2}}\ensuremath{\rightarrow}^{2}D_{\frac{5}{2}})=8.8,6.5,10.4, \mathrm{and} 30$; $Q(^{2}D_{\frac{3}{2}}\ensuremath{\leftarrow}^{2}D_{\frac{5}{2}})=5.8,4.0,6.9, \mathrm{and} 18$, in units of ${10}^{\ensuremath{-}14}$
cm2 for He, Ne, Ar, and Rb, respectively. Cross sections for the effective quenching of the
2D states were also determined.
The 8
2S state of rubidium is selectively populated by stepwise excitation using light from a rubidium lamp and a tunable dye laser. Excitation transfer from the 8
2S to the 6
2D state is studied in a glass cell containing rubidium vapor and noble-gas atoms at different pressures and ground-state rubidium atoms as perturbers. The thermally averaged cross sections for excitation transfer (in units of ${10}^{\mathrm{\ensuremath{-}}15}$
cm2) are 0.13\ifmmode\pm\else\textpm\fi{}0.05, 3.0\ifmmode\pm\else\textpm\fi{}1.2, 2.2\ifmmode\pm\else\textpm\fi{}0.9, 1.7\ifmmode\pm\else\textpm\fi{}0.7, and 4.3\ifmmode\pm\else\textpm\fi{}2.6 for the noble gases He, Ne, Ar, Kr, and Xe, respectively, and (6.7\ifmmode\pm\else\textpm\fi{}3.0)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$
cm2 for rubidium atoms. The results show that the excitation-transfer cross sections for intermediately excited states cannot be accurately scaled from simple models.