High Resolution Image Download MS PowerPoint Slide Research on the electric quadrupole frequency shift mechanism and nuclear spin relaxation of 129 Xe– 131 Xe in alkali metal atomic vapor cells fabricated using microelectromechanical systems (MEMS) technology remains in its early stages. Therefore, an in-depth investigation in this field is crucial for enhancing the performance of miniaturized atomic gyroscopes and other quantum devices. This study provides a comprehensive analysis of the electric quadrupole frequency shift and relaxation of 129 Xe– 131 Xe nuclear spins in a stemless cubic MEMS vapor cell. To elucidate the microscopic characteristics of wall interactions, nuclear spin quadrupole interactions with mixed silicon and glass surfaces in MEMS vapor cells were examined. The influence of the angle between the vapor cell’s geometric axis and the applied magnetic field on the electric quadrupole frequency shift was investigated, leading to the determination of the vapor cell’s asymmetry parameter η and the average twist angle ⟨ θ ⟩ of nuclear spin-wall collisions. Furthermore, the temperature dependence of the electric quadrupole frequency shift in 131 Xe atoms was characterized, enabling the extraction of the desorption activation energy ( E A ) of 131 Xe on the MEMS vapor cell surface. By analyzing the free induction decay (FID) signals of 129 Xe and 131 Xe at varying temperatures, the relationship between their relaxation rates and temperature was established. These findings offer valuable insights for optimizing nuclear spin relaxation times in microatomic gyroscopes.
Spin-exchange collisions between polarized 87 Rb atoms and unpolarized 129 Xe nuclei have been used to produce nuclear spin polarized 129 Xe. Measurements of the longitudinal relaxation rate of 129 Xe nuclear polarization have been carried out in a 5.7G magnetic field. The present results show that the nuclear spin relaxation rate of 129 Xe in 87 Rb vapor is proportional to the density of the 87 Rb atoms, and the nuclear spin relaxation rates of 129 Xe induced by the 87 Rb atoms depend on the pressure of the buffer gas N 2 .
Cross sections for relaxation of circular and linear polarization of
62P23 cesium atoms, induced in collisions with ground-state He, Ne, Ar, and Xe, have been determined by Zeeman scanning techniques. A fluorescence cell containing low-pressure cesium vapor together with a buffer gas was irradiated with circularly or linearly polarized 8521-\AA{} Cs resonance radiation, producing excited and polarized Cs atoms which became depolarized in subsequent collisions with the buffer-gas atoms. The resulting depolarization of the cesium resonance fluorescence was monitored in relation to buffer-gas pressure (0-10 Torr) and to the strength of the ambient magnetic field (0-10 kG). At low fields at which the nuclear spin $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ is coupled to the electronic angular momentum $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$, the measurements yielded depolarization cross sections
Q(circ.) and
Q(lin.), which agree within experimental error with theoretical values calculated for spin-coupled conditions. At kilogauss fields with $\stackrel{\ensuremath{\rightarrow}}{\mathrm{I}}$ and $\stackrel{\ensuremath{\rightarrow}}{\mathrm{J}}$ decoupled, the experiments produced cross sections for disorientation and disalignment, which are also in satisfactory agreement with the appropriate theoretical predictions. The results indicate that the nuclear spin has a more pronounced effect on the collisional relaxation of the atomic dipole than of the quadrupole.
Estimates of the Rb-
131Xe spin-exchange cross section have been obtained by observing the nuclear spin relaxation of
131Xe in the presence of a Rb vapor. Nuclear spin relaxation of
131Xe due to the presence of a foreign buffer gas and the relaxation rate on the glass walls of the cell have also been observed.
The nuclei of gaseous
129Xe atoms are polarized by spin exchange with optically pumped Rb vapor. The Xe gas is subsequently frozen. The nuclear polraizations of up to 25% are largely unaffected by freezing. The spin-lattice relaxation time
T1 was measured as a function of temperature, magnetic field, and isotopic composition. At 77 K and 1800 G,
T1 is limited to about 3 h by a new relaxation mechanism. The potential for accumulating large samples with even higher polarizations makes laser-polarized Xe ice promising for a wide variety of new experiments.
A new optical method for studying the spin relaxation of optically aligned rubidium vapor is described. In this method, the pumping radiation, consisting of circularly polarized
D1 resonance radiation, is suddenly shut off and then turned on again after a known time interval. The relaxation which takes place during the interval of darkness causes the vapor to become more opaque to the pumping radiation at a rate which is determined by the relaxation time. A large degree of alignment, as well as a relaxation time of about 80 milliseconds, were observed in a closed-off evacuated cylindrical glass cell completely lined, except for
2001 of the wall area, with a thin film of tetracontane (
C40H82). The variation of relaxation time with buffer gas pressure was studied in this cell and in an unlined glass cell. From the observations with the unlined cell, diffusion coefficients for rubidium in neon and argon of 0.31
cm2/sec and 0.24
cm2/sec, respectively, can be deduced. Observed cross sections for disorientation collisions between aligned ground-state rubidium atoms and neon, argon, krypton, and xenon atoms are 5.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}23}$
cm2, 3.7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}22}$
cm2, 5.9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}21}$
cm2, and 1.3\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}20}$
cm2, respectively. In the evacuated tetracontane-lined cell, the relaxation time decreased by 30% for a tenfold increase in rubidium vapor pressure. An explanation for this relatively weak dependence is suggested. The longest observed relaxation time was approximately 0.4 seconds in a tetracontanelined cell filled with neon to a pressure of 3 cm Hg.