We have measured the circular polarization of light emitted from both atomic H and molecular ${\mathrm{H}}_{\mathrm{2}}$ after bombarding ${\mathrm{H}}_{\mathrm{2}}$ with longitudinally polarized electrons. For both atomic and molecular fluorescence near threshold we observe a circular polarization as great as 10% of the electron polarization. This represents the first direct observation of spin transfer in electron-molecule collisions.

• Received 6 June 2003

DOI:https://doi.org/10.1103/PhysRevLett.92.093201