By directly observing the nuclear polarization of I29 Xe, the efficiency r? of spin exchange between optically pumped Rb spins and 129 Xe nuclei has been measured. It is found that I/77 = 23 ± 4 rubidium D { resonance-line photons are required to polarize a 129 Xe nucleus when long-lived van der Waals molecules are unimportant. The binary spin-exchange cross section deduced from our measurements is cr ex = (7.3 ± 1.1)x 10" 21 cm 2 .
A new and unusual phenomenon which we call light narrowing is reported and discussed in this paper. We discovered this effect in dense, spin-polarized cesium vapor optically pumped with a cw blue dye laser beam tuned to 0 the second resonance D, line (4593 A), We observe a significant narrowing of the radio-frequency power-broadened magnetic resonance lines (linewidths narrow by as much as a factor of 2.5) when the intensity of the circularly polarized incident dye laser beam is increased by either focusing;the beam or by the removal of attenuating filters from the focused beam. The magnetic resonance linewidths in spin-polarized cesium vapor were measured over a wide range of cesium number densities (5)&10". cm '& [Cs] &1)&10"cm '). This corresponds to cesium spinexchange rates of 4.5)&10' to 9X 10' sec ', For low cesium number densities (5X10" ([Cs](3)(10"cm ') the light-narrowing effect is large (a factor of 2.5) and independent of [Cs]. In the region of 3 X 10" to 1)& 10" cm ' in number densities, the light-narrowing effect decreases with increasing [Cs]. At high cesium number densities ([Cs]) 1&10"cm ') this light-narrowing effect almost completely disappears. In the limit of low-radio-frequency power the magnetic resonance linewidths for focused and unfocused dye laser beam are nearly the same.Experimental observations on this new effect are presented in detail. In the latter part of this paper a self-contained theoretical treatment of the light-narrowing effect is developed, Using Bloch equations in the presence of optical pumping, spin relaxation (diffusion, electron randomization), rapid spin exchange, and radio-frequency magnetic field, expressions for magnetic resonance line shapes are derived. In general, we find good agreement between our experimental results and the theory.
Continuous-wave lasing in optically pumped atomic cesium and rubidium vapor is observed without the use of any feedback mirrors. The stimulated emission in a number of infrared wavelengths is restricted to a very narrow angle in both the forward and backward directions.
We have discovered a novel, spatially propagating wave front which is generated by laser pumping of an optically thick medium to a state of complete transparency. The wave front consists of a moving band of fluorescent light which marks the location of atoms which are being pumped. The wave-front velocity v, the photon flux /Q, the atomic number density iV, and the number n of photons absorbed per atom are related by f =/o x(JVn)"^
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.