Induced nuclear spin polarization $P$ by hyperfine interaction following passage of 0.5 μA 300-keV beams of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}_{}^{+}{}_{}{}^{}$, ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}_{}^{+}{}_{}{}^{}$, and ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}_{}^{+}{}_{}{}^{}$ through single tilted carbon foils yields $\left|P\right|=(0.4\mathrm{}\pm 0.8)\%, (3.2\mathrm{}\pm 0.6)\%, \mathrm{and} (5.7\mathrm{}\pm 0.9)\%$, respectively. The nuclear polarizations were enhanced by passage through two tilted foils, and the sign of the polarization flipped by a simple flip of the foil direction with respect to the beam direction. From quantum-beat measurements with circularly polarized light, experimental quantum beat frequencies $\omega =6790\mathrm{}\pm 570 \mathrm{and} 747\pm 62$ MHz for the unresolved 6578-6583 Å doublet in CII, and $\omega \left(5667\mathrm{} \AA \right)=2860\mathrm{}\pm 240$, $\omega \left(5680\mathrm{} \AA \right)=4810\mathrm{}\pm 40$ MHz in NII are determined.

NUCLEAR REACTIONS Beam-foil interaction C(${}_{}{}^{12,13}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{12,13}{}_{}{}^{}\mathrm{C}$), C(${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$), $E=0.3-0.4\mathrm{}$ MeV; measured optical CP and quantum beats. Deduced nuclear $P$.

• Received 27 April 1981

DOI:https://doi.org/10.1103/PhysRevC.25.1476