Anomalous light-induced drift of potassium in Ne plus rare-gas mixtures

Abstract

We report anomalous light-induced drift of potassium vapor in mixtures of Ne with another rare gas. The drift velocity versus laser frequency curve shows a strong deviation from the dispersion curve predicted by the standard theory of light-induced drift based on velocity-independent collision rates. The observed drift velocity versus frequency curves have three zero-crossings. For a qualitative explanation of the results, a strong collision model with velocity-dependent collision rates is used. The partial pressures that cancel normal light-induced drift also provide accurate ratios of cross section for potassium collisions with the various buffer gases. The observation of anomalous light-induced drift in a simple atomic system offers the opportunity to relate the results to potential curves. \textcopyright{} 1996 The American Physical Society.