Measurement of Spin-Exchange Cross Sections forCs133,Rb87,

Abstract

This paper reports measurements to determine the spin-exchange cross section for collisions between like alkali atoms. The spin-exchange cross section is determined for Cs , Rb 87 , Rb 85 , K 39 , and Na 23 . The lifetime of the alkali atoms in the Zeeman sublevels of the ground-state hyperfine levels is dominated by spin-exchange collisions. The spin-exchange collision rate is therefore reflected by the linewidth of the microwave absorption spectrum observed in the magnetic dipole transitions between various of the Zeeman sublevels. The measurements employed an X-band electron paramagnetic resonance spectrometer. The alkali metal was distilled into a sample bulb which was placed inside a Dewar in a resonant cavity. The bulb was then heated to a temperature corresponding to an equilibrium vapor density of approximately 10 5 alkali atoms/c.c. and the microwave absorption spectrum was recorded. In order to relate the spin-exchange rate to a cross section, it is necessary to determine the alkali density. This was done by comparing the intensity of the alkali EPR absorption to that of a weighed and oriented copper sulfate crystal. For Cs 33 and Rb 87 , interpretation of the linewidth data is complicated by the fact that the transitions occur in a region where there is appreciable mixing of the high-field spin states by the hyperfine interaction. A density-matrix description of spin exchange which corrects for this intermediate field mixing is discussed, and the corrections are applied to the measured cross sections for two transitions in Cs 133 and Rb 87 . Relative cross sections, referred to that of Na 23 , are also given.

High-Sensitivity Atomic Magnetometer Unaffected by Spin-Exchange Relaxation

“…(4). From the fit we obtain T SE 7:6 s, in good agreement with existing measurements of the spinexchange cross section [15,16]. The magnetometer can be operated in several modes to measure different components of the magnetic field.…”

The polarization and the fundamental sensitivity of 39K (133Cs)-85Rb-4He hybrid optical pumping spin exchange relaxation free atomic magnetometers

“…where A represents alkali-metal atom 39 is the relative velocity between the alkali atoms and quench gas N 2 respectively, the reduced mass of alkali atoms and quench gas N 2 is m alkali−N 2 = m alkali m N 2 m alkali +m N 2 , the relative velocity between the alkali atoms and buffer gas 4 He isv alkali−He = 8κ B T πm alkali−He , the reduced mass of alkali atoms and buffer gas 4 He is m alkali−He = m alkali m He m alkali +m He , k SE for different alkali metal atoms are nearly the same [26][27][28][29][30] Substitute equation (2) into equation (3), we obtain…”

Quantitative study of optical pumping in the presence of spin-exchange relaxation

“…From the Cs-Cs spin-exchange cross section σ se = 2.06 × 10 −14 cm 2 reported in Ref. [19] one can calculate the spin-exchange rate according to…”