Yasushi Yamauchi

Spin Polarization Measurement of Metastable He 23S1 Atoms in He Discharge

A method of measuring the polarization of metastable He 23S1 atoms (He*) in a He discharge is improved. He* density in each magnetic substate, i.e., mJ=+1, 0, -1, is estimated by measuring the attenuation of circularly and linearly polarized 1083 nm laser beams that are both tuned to the transition of He* 23S1 to 23P0 (the D0 line).

Electron emission from Na/Fe(100) surfaces by deexcitation of spin-polarized helium metastable atoms

A pulsed helium metastable atom beam was generated by the pulsed nozzle-skimmer discharge and a high degree of spin polarization of the helium beam was obtained using the optical pumping method. Spin polarization of the outermost surface electron was detected for clean and sodium covered Fe(100) films deposited on MgO(100) by measuring the secondary electrons ejected by the irradiation of the spin-polarized helium metastable atom beam. Secondary electrons correspond to the Fermi level for a clean iron surface and those corresponding to the Na 3s level for the sodium-covered surface show a positive asymmetry, which indicates the negative polarization of electrons at these levels. The negative polarization of the Na 3s electrons rapidly decreases with the thickness increasing of the Na layer up to 0.5 ML but remains almost constant at a higher coverage (3ML).