Pressure shifts and broadening of the Cs D1 and D2 lines by He, N2, and Xe at densities used for optical pumping and spin exchange polarization

The production of hyperpolarized gases by spin-exchange optical pumping (SEOP) requires exact knowledge of the alkali metal's D1 absorption profile and the degree to which it is broadened and shifted by varying buffer gas composition and pressure. We have measured these parameters for cesium (Cs) in the presence of Xe, N2, and H4 e perturber gases at densities up to 10 amagats. The effects of these gases are important as Cs is attracting increasing interest for SEOP applications. Our measurements were made using simple white-light illumination of the Cs vapor while characterizing the D1 (6 S1/2 to 6 P1/2) and D2 (6 S1/2 to 6 P3/2) resonances using a high-resolution optical spectrometer. For the Cs D1 resonance at T=120 °C, we report shifts from the 894.59 nm vacuum wavelength caused by H3 e, H4 e, N2, and Xe of -0.017±0.003, -0.013±0.002, 0.026±0.002, and 0.029±0.002 nm/amagat. We also report the shifts for the D2 resonance as well as pressure broadening coefficients for both resonances. © 2008 American Institute of Physics.

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Author Bastiaan Driehuys Radiology