Abstract The magnetic-resonance frequency shifts of Cs and K atoms induced by spin exchange at optical orientation of atoms are calculated. The situation under study is characteristic of a tandem magnetometer based on a mixture of cesium and potassium atoms in one working chamber.
Abstract Collisions of alkali atoms in the ground state are accompanied by the exchange of electron polarization between the colliding atoms, which lead to the polarization transfer between particles. As a result of this process, the electronic orientation is transferred from the spin oriented atoms to unpolarized atoms, along with the polarization transfer, the magnetic resonance frequency shifts of polarized atoms occur too. In this work the magnetic resonance frequency shifts of arising from spin exchange collisions in a mixture of alkali potassium and rubidium atoms at the optical orientation of atoms are calculated. The situation when optical pumping by resonant polarized radiation is carried out only for atoms of the one kind is considered. The spin exchange process between alkali atoms was described in the formalism of the complex cross section for spin exchange process. The real and imaginary parts of the complex cross section were calculated using the interaction potentials of alkali atom dimers. The calculation of the frequency shifts is carried out on the basis of data on the interaction potentials for the following pairs of alkali atoms K-K, K-Rb and Rb-Rb. Maxwell averaging of the cross sections over the velocities was done and the temperature dependences of the magnetic resonance frequency shifts for K and Rb atoms were plotted.
Subject of study. Magnetic resonance frequency shifts caused by spin exchange collisions involving optically oriented alkali atoms in the ground state are studied. Aim of study. Spin-exchange collisions involving optically oriented pairs of alkali atoms of different types are theoretically studied to determine the shifts in the magnetic resonance line frequencies as a function of temperature for various pairs of alkali atoms under various optical orientation conditions in order to determine optimum constraints for the construction of quantum magnetometers with optical pumping using mixtures of alkali atoms. Method. Collisions between optically oriented alkali atoms are analyzed within the framework of quantum scattering theory, and data on the interaction potentials of alkali-atom dimers are used to calculate the scattering phases for collisions involving these potentials and the imaginary parts of the complex spin-exchange cross-section. The resulting cross sections as a function of energy were used to determine the magnetic resonance frequency shifts as a function of temperature. Main results. The magnetic resonance line frequency shifts for the following pairs of alkali atoms were obtained as a function of temperature: 39K−133Cs, 39K−85Rb, and 133Cs−85Rb. The shift in the magnetic resonance line involving the F=1 hyperfine state for a 39K−85Rb alkali-atom pair was found to pass through zero near temperature 480 K. Practical significance. The results obtained in this paper can be used to develop zero-spin-exchange-shift quantum electronic devices based on the optical orientation of atoms. In particular, it is possible to develop co-magnetometers based on the optical orientation of alkali atoms.
Collisions between sodium and potassium atom in the conditions of optical orientation of potassium atoms are considered. Because of collisions, the spin exchange occurs between colliding atoms, which leads to a magnetic resonance frequency shift of Na atoms. Calculations reveal that the magnetic resonance frequency shift of Na atoms in the upper hyperfine state (F = 2) changes its sign from negative to positive upon an increase in the temperature in the absorption chamber from 300 to 500 K and passes through zero near temperature T ~ 450 K, while the frequency shift of the lower hyperfine state (F = 1) remains negative in the entire range of investigated temperatures. An analogous effect is observed for the first time in the case in which the main contribution to the magnetic resonance frequency shift comes from the spin exchange.