Direct Optical Resolution of the Recoil Effect Using Saturated Absorption Spectroscopy

Abstract

The recoil-induced spectral doubling of the C${\mathrm{H}}_{4}$ saturated absorption peaks at 3.39 \ensuremath{\mu}m has been clearly resolved. A working resolving power of 8 \ifmmode\times\else\texttimes\fi{} ${10}^{10}$ (1 kHz half width at half-maximum), achieved with aberration-compensated parabolic optics of 32 cm diam, was available to study the height ratio and splitting of the recoil peaks. The resolved Dopplergenerated level crossings are not recoil doubled and give improved hfs information. We derive new, exact equations relating the atomic natural frequency to laboratory resonance frequencies.