On the Silicon Oxide Bands

Pankhurst has described a band spectrum believed by him to belong to an oxide of silicon, possibly Si${\mathrm{O}}_2$. A better excitation of the same bands has been obtained from a similar source (a high voltage uncondensed discharge through a constriction in a quartz tube), but in helium gas instead of hydrogen. These bands have been photographed on the 30-foot, 30,000 lines per inch Chicago grating spectrograph. A band near $\lambda 3840$ has been resolved in the first and second orders and found to be a (0,0) transition, overlapped by a weak (1,1) transition, of the type ${}_{}{}^2{}_{}{}^{}\Sigma \to {}_{}{}^2{}_{}{}^{}\Sigma$, having the constants $\left\{\nu \mathrm{}\right(0,0)=26,015.05\mathrm{} {\mathrm{cm}}^{-1\mathrm{}},,\nu \mathrm{}(1,1)=25,991.44\mathrm{}{\mathrm{cm}}^{-1\mathrm{}},\}\{{B_0}^{\prime }=0.7180\mathrm{}{\mathrm{cm}}^{-1\mathrm{}},,{B_1}^{\prime }=0.704\mathrm{}{\mathrm{cm}}^{-1\mathrm{}},\}\{{B_0}^{\prime \prime }=0.7253\mathrm{}{\mathrm{cm}}^{-1\mathrm{}},,{B_1}^{\prime \prime }=0.712\mathrm{}{\mathrm{cm}}^{-1\mathrm{}}.\}$ The coefficients of the spin doubling for the two states are ${{\gamma }_0}^{\prime }=+0.012\mathrm{} {\mathrm{cm}}^{-1\mathrm{}}$, ${{\gamma }_0}^{\prime \prime }=+0.002\mathrm{}$ or ${{\gamma }_0}^{\prime \prime }=+0.022\mathrm{} {\mathrm{cm}}^{-1\mathrm{}}$, the value of ${{\gamma }_0}^{\prime \prime }$ not certainly fixed as between these two alternatives. The doublet structure and the $B$ values prove that the emitter is Si${\mathrm{O}}^{+}$. Other bands at $\lambda 4270$ have been resolved with weak intensity and tentatively ascribed to Si${\mathrm{O}}_2$.