Zur Bestimmung der Spin-Polarisation aus Transparenz-Messungen beim Optischen Pumpen

A simple method of measuring the degree of polarization achieved by optical pumping has been described recently for the case of sodium vapor, illuminated with the single circularly polarizedD ₁ line. The assumption had to be made, however, that the atomic absorption cross sectionQ, depending on the degree of polarizationP and the frequency of lightν, may be approximated byQ(P, ν)=(1?P)·Q(P=O,ν). The purpose of this paper is to discuss the qualification of this assumption. A theoretical analysis of the pumping process is tried, showing that the measured polarization corresponds in good approximation to the degree of the valence electron spin polarization. — For the case of weak absorption and equal intensity of the two hyperfine components of theD ₁ line a diagramm is given, relating the measured polarization to the polarization of the nuclear spin.