[Measurement of the Rb[5P3/2(F'=4)] hyperfine level nonradiative decay rate near a metallic film with laser retrofluoresence spectroscopy].
Jing Liu, Jing-Tao Xin, Kang Dai +1 more
The signals of the hyperfine 85Rb[5P3/2(F' = 2,3,4) --> 5S1/2(F = 3)] transition lines in a diode laser induced retrofluorescence spectrum at the interface between glass and Rb vapor were experimentally identified and investigated. The glass-vapor interface was considered as two distinct regions, a wavelength-thickness vapor layer joined to the surface and a more remote vapor region. The first region was analyzed as a spectral filter that annihilates the absorbed photons and the second one as a rich spectral light source. The experimental setup is described. A Rb reference cell (T = 293 K) was used. A part of the laser beam scanned the 5S1/2(F = 3) --> 5P3/2(F' = 2,3,4) transition. The Doppler broadened absorption profile (FWHM = 510 MHz) was determined. The laser detuning of the profile-center relative to the F = 3 --> F' = 4 transition was about 70 MHz. Another laser beam was directed to the entrance cell window. The resonant retrofluorescence S(ob)(upsilon(L)) as a function of laser detuning for a cell temperature approximately 130 degrees C and laser power 0.4 mW was obtained. We can extract the experimental signal sexp(n) (upsilon(L)) originating from the near-field region by subtracting signal S(T) (upsilon(L)) originating from the far-field region from the total experiment signal S(ob)(upsilon(L)). A fit of the normalized profile of the data corresponding to the spectral band centered on the F' = 4 --> F = 3 hyperfine transition line was obtained by using a Lorentzian distribution function with GammaRF = 50 MHz full width at half-maximum. The role played by different relaxation processes contributing to the retrofluorescent atomic linewidth was characterized. The authors summed up the corresponding spectral broadening and obtained the relation GammaRF = Gamman + Gammacoll + Gammanr, where Gammacoll is the resonance collisional broadening of the hyperfine line, and Gammanr is an additional broadening induced by the nonradiative energy-transfer phenomena of the excited atoms near the cell window surface. To evaluate Gammacoll, we used the relation Gammacoll = gammaRb - RbN, where gammaRb - Rb is line broadening parameter, and N is Rb atom number density. The effective nonradiative relaxation rate of the 5P3/2(F' = 4) energy hyperfine level was estimated to be AF(nr) = 4 --> F = 3 = 2.4 x 10(8) s(-1). The value of A(nr) seems relatively large compared to the spontaneous emission rate A(5P3/2 --> 5P1/2) = 1.4 x 10(7) s(-1).
•Jan 1, 2009•0 citations