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 cross sections for excitation transfer between the 62P fine structure levels of rubidium, induced in collisions with ground state rubidium atoms, have been measured using a nitrogen laser pumped dye laser as the optical excitation source in a fluorescence experiment. Rubidium vapor was irradiated with each component of the 2P rubidium doublet in turn, and measurements of the relative intensities of fluorescence yielded the following cross sections: [Formula: see text] These results are consistent with the empirical relationship between the magnitude of the cross sections and the fine structure splitting that has previously been established for the alkalis.
Cross sections for
72D and
82D fine-structure mixing in Rb, induced by collisions with various ground-state atoms and
N2 molecules, have been determined using methods of atomic fluorescence. Rb vapor, pure or mixed with a buffer gas, was irradiated in a glass fluorescence cell with pulses of radiation from a
N2 laser-pumped dye laser, populating a
2D fine-structure state by two-photon absorption. The resulting fluorescence included a direct component arising from the optically excited state and a sensitized component due to the collisionally populated fine-structure state. Measurements of relative intensities of the two components in relation to buffer-gas pressure yielded the following cross sections (in units of ${10}^{\ensuremath{-}14}$
cm2): $Q({7}^{2}{D}_{\frac{3}{2}}\ensuremath{\rightarrow}{7}^{2}{D}_{\frac{5}{2}})=14.1,15.5,\mathrm{and}10.0$; $Q({7}^{2}{D}_{\frac{3}{2}}\ensuremath{\leftarrow}{7}^{2}{D}_{\frac{5}{2}})=9.0,10.5,\mathrm{and}6.9$, for Kr, Xe, and
N2, respectively; $Q({8}^{2}{D}_{\frac{3}{2}}\ensuremath{\rightarrow}{8}^{2}{D}_{\frac{5}{2}})=8.9,4.9,12.4,24.9,25.8,12.1,\mathrm{and}43.1$; $Q({8}^{2}{D}_{\frac{3}{2}}\ensuremath{\leftarrow}{8}^{2}{D}_{\frac{5}{2}})=5.8,3.2,9.4,15.1,17.6,8.3,\mathrm{and}28.5$, for He, Ne, Ar, Kr, Xe,
N2, and Rb, respectively. Cross sections for the effective depopulation of the
2D states were also determined.
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.
A diode-laser fluorescence experiment was performed in order to study fine-structure transitions between 5 2 P states of rubidium atoms colliding with ground-state potassium or caesium atoms. The Rb (5 2 P 3 2/) state was optically excited and the intensity ratio of sensitized to direct fluorescence was measured. The obtained cross sections for the excitation energy transfer Rb( 2 P 3 2/) to Rb( 2 P 1 2/) induced by collisions with K and Cs (T=573 K) are sigma =54 AA 2 +or-30% and sigma =15 AA 2 +or-30%, respectively. Assuming detailed balancing, the cross sections for the reverse process Rb( 2 P 1 2/) to Rb( 2 P 3 2/) are sigma =60 AA 2 +or-30%, and sigma =16.5 AA 2 +or-30% for K and Cs, respectively.
Cross sections for 6^D, 7^D and 8^0 fine-structure mixing in Rb, induced in collisions with various ground-state atoms and N2 molecules, have been determined using methods of atomic fluorescence.Rb vapour, pure or mixed with a buffer gas, was irradiated in a glass fluorescence cell with pulses of radiation from a N2 laser-pumped dye laser, populating a fine-structure state by two-photon absorption.The resulting fluorescence included a direct component emitted in the decay of .the optically excited state and a sensitized component due to the col1isional1y populated fine-structure state.Measure ments of relative intensities of the two components in relation to buffer gas (or Rb vapour) pressure yielded the following cross sections.-14 2 Inelastic Cross sections (10 cm ) process Rb He Ne Ar Kr Xe I would like to express sincere thanks to Professor L.