The frequency shifts of the (F = 2, m = 0)--(F = 3, m = 0) transition in the 5 /sup 2/S/sub 1//sub ///sub 2/ state have been calculated for the /sup 85/Rb isotope on perturbation of the unpolarized light of the D1 line (lambda = 794.7 nm) of a spectral lamp as functions of the temperature of the absorbing vapor, the pressure of the buffer gas, and the length of the cell. The change in intensity and spectral distribution in the emitted light as it passes through the cell, containing rubibium vapor, has been taken into account. Experimentally measured contour lines of standard spectral lamps were used in the calculations.
Abstract Using a Rb cell and a wavemeter, with a Doppler-free two-photon transition near 993 nm, we have measured the four hyperfine components (two isotopes, Δ F = 0) of the 5S–6S transition, finding the absolute energies of those transitions to a spectral resolution of 0.002 cm −1 = 60 MHz. We find the (87 minus 85) isotope shift of the 5S–6S transition to be +94(12) MHz. Using our single frequency cw laser with focused intensity up to 10 4 W cm −2 at the cell, we find no AC Stark or light shift of the lines at 6 MHz spectral resolution. We find no density shift of the lines at 6 MHz spectral resolution, for a range of Rb atom densities from 3 × 10 11 to 5 × 10 13 atoms/cm 3 .
The linewidth and frequency associated with the ground state hyperfine energy fo Rb 87 has been studied. A stable single mode semiconductor laser is used to optically pump Rb, in order to obtain a highly collimated, monochromatic light source. The laser is stabilized by locking its optical frequency to the Rb absorption line center. The dependence of the hyperfine frequency and resonance linewidth have been measured as a function of temperature, light intensity and microwave power; and a theoretical description of the linewidth vs. temperature data is presented. Keywords: Optical pumping; Rubidium; Frequency standard; Frequency shift; Light shift; Density matrix; Buffer gas; Linewidth; and Magnetic resonance.
The temperature dependence of the spectral profile of the 87Rb D1 line (λ = 794.8 nm) observed by a Fabry-Perot interferometer has been discussed by considering the self-absorption mechanism in the lamp. The Rb lamp is assumed to be composed of two separated portions: One is a spherical core of emitting Rb atoms and the other is an outer layer of the same kind of absorbing atoms surrounding the core. The temperature dependence of the emitted light intensity, intensity difference between two hyperfine peaks, and asymmetry of the self-absorbed profiles are systematically explained in the temperature range of 75 to 125°C. The equivalent absorbing atom layer near the lamp surface is estimated to be 0.5 mm in this model.
In this paper we calculate the effect of spin-exchange collisions in alkali-metal vapors. In the framework of the high-energy approximation, we evaluate the spin-exchange cross sections related to the line broadening and to the frequency shift of the ground state hyperfine transition. We do the calculation for the four isotopes,
23Na,
39K,
87Rb, and
133Cs. The results are used in particular to evaluate the spin-exchange frequency shift in Rb vapor cell frequency standards used in many applications. It turns out that, due to possible fluctuations in the atomic density, spin exchange may affect significantly the medium and long term frequency stability of the frequency standard.
The
5S1/2→6P3/2 transition of rubidium at
420 nm is a promising candidate for a portable warm-vapor all-optical atomic clock. Despite recent precision spectroscopy studies at
420 nm in Rb, an experimental determination of the saturation intensity of this transition has not yet been reported. The saturation intensity is a fundamental parameter that influences the identification of a potential clock transition frequency in terms of optimizing various intensity-dependent parameters and connected systematics. In this work, we report the first experimental measurement of the saturation intensity of the
420 nm transition in Rb, obtaining
(23.18±0.28) mW/cm
2 for the
87Rb
F=2→F′=3 transition and
(25.56±0.37) mW/cm
2 for the
85Rb
F=3→F′=4 transition, in excellent agreement with theoretical predictions. We further investigate the temperature dependence of the Doppler-free Lamb-dip amplitude and linewidth over
59.03 ± 0.37 -
91.20 ± 0.90∘C in a
100 mm commercial vapor cell, identifying around
82.02 ± 0.73∘C as the optimal operating temperature, where the signal-to-noise ratio of the Lamb-dip amplitude with temperature reaches a maximum and the observed Lamb-dip linewidth exhibits a minimum. We also present precise measurements of the magnetic-dipole (
A) and electric-quadrupole (
B) hyperfine constants of the
6P3/2 state for both isotopes, with the measured values being consistent with previously reported values for the hyperfine constants.
Abstract A cell with a submicron thickness was used to measure the broadening and shift of the D1 and D2 lines of Rb atoms by neon. The resolution of hypefine components is achieved by a combination of two techniques. First, the Rb vapor column thickness in the direction of propagation of the laser radiation was chosen equal to half of its wavelength λ under conditions of resonance with the atomic transition frequency. For rubidium atoms λ/2 ~ 400 nm. At a nanocell thickness L ~ λ/2, in the transmission spectrum A(ν), the spectral lines of atomic transitions are narrowed due to the exclusion of Doppler broadening. Second, further narrowing of the detected signals was achieved by the double differentiation of the transmission spectrum, A''(ν). The transmission spectra of pure rubidium vapor and rubidium vapor with the addition of neon have been measured at different pressures. The measured values of the shift coefficients of the D1 and D2 lines of rubidium in the presence of Ne were –1.1 ± 0.2 MHz/Torr and –2.1 ± 0.2 MHz/Torr, respectively. The broadening coefficients of the D1 and D2 lines coincide and are equal to 10 ± 1 MHz/Torr. Due to its high spectral resolution, this technique allows separate measurements for each individual transition.