Precision measurement of the oscillator strength of the cesium-6 S-2(1/2)-> 5 D-2(5/2) electric quadrupole transition in propagating and evanescent wave fields

Hyperfine-structure-resolved absorption spectra of the 6 S-2(1/2) --> 5 D-2(5/2) of cesium atoms have been observed with a temperature-controlled cell and a diode laser. From a comparison with the absorption of the D-2 transition at the same atom density range, the oscillator strength of the electric quadrupole transition was determined to be (4.69 +/- 0.05) X 10(-7). Reflection spectra of the same transition have also been observed in the partial and total reflection regimes with a reflection cell. An increase in the apparent oscillator strength was observed for total reflection with an increase in the angle of incidence, by a factor up to 1.5 at theta(c) + 83.8 mrad and 2.4 at theta(c) + 107.5 mrad for s and p polarizations, respectively, where theta(c) is the critical angle. The observed enhancement is ascribed to the incidence-angle-dependent wave vector and polarization vector of the evanescent wave.