Angle-resolved photoemission from the NaCl (100) face

The angle and energy distribution of photoelectrons from the (100) face of NaCl single crystals were measured for photon energies ranging from 15 to 30 eV by use of synchrotron radiation. Critical points of the band structure along the line $\Gamma \Delta X$ of the Brillouin zone were derived from the data. The energies measured from the top of the valence band in eV are the following: $E\left(X_{}^{\prime }{}_4{}^{}\right)=-2.4\mathrm{}\pm 0.2$, $E\left(X_{}^{\prime }{}_5{}^{}\right)=-1.4\mathrm{}\pm 0.2$, $E\left(X_1\right)=11.4\mathrm{}\pm 0.5$, $E\left(X_3\right)=12.0\mathrm{}\pm 0.5$, $E\left(X_{}^{\prime }{}_4{}^{}\right)=17.0\mathrm{}\pm 0.5$, $E\left(\Gamma _{}^{\prime }{}_{25}{}^{}\right)=17.2\mathrm{}\pm 0.2$; and a minimum of the third conduction band on ${\Delta }_1$ at 13.7 ± 0.5 eV. The assignment for $E\left(X_5\right)$ (21 eV) and $E\left({\Gamma }_{12}\right)$ (18.7 eV) is less certain. The evaluation is facilitated by the fact that many of the Bloch states on the $\Gamma \Delta X$ line do not contribute to the photoemission in the [100] direction since they do not contain the appropriate plane wave components.