New measurements of the wave-lengths of the band heads attributed to the oxides of Mg, Ca and Sr have been made from moderate dispersion spectrograms. For each of these molecules the bands have been classified into two systems. The equations of the band heads in terms of half-quantum numbers for the different systems are as follows: MgO, red bands: $\{\nu =16,418.06\mathrm{},+\{821.95(v^{\prime }+\frac{1}{2})-4.05\mathrm{}{(v^{\prime }+\frac{1}{2})}^2\left\}\right\}\{-\{665.74(v^{\prime \prime }+\frac{1}{2})-4.41\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2\left\}\right\}$ MgO, green bands: $\{\nu =19,944.82\mathrm{},+\{811.67(v^{\prime }+\frac{1}{2})-3.74\mathrm{}{(v^{\prime }+\frac{1}{2})}^2\left\}\right\}\{-\{771.42(v^{\prime \prime }+\frac{1}{2})-4.81\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2\left\}\right\}$ CaO, blue bands: $\{\nu =23,817.62\mathrm{},+\{726.53(v^{\prime }+\frac{1}{2})-11.66\mathrm{}{(v^{\prime }+\frac{1}{2})}^2\left\}\right\}\{-\{811.28(v^{\prime \prime }+\frac{1}{2})-6.60\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2\left\}\right\}$ CaO, ultraviolet bands: $\{\nu =28,849.13\mathrm{},+\{565.06(v^{\prime }+\frac{1}{2})-4.48\mathrm{}{(v^{\prime }+\frac{1}{2})}^2\left\}\right\}\{-\{725.37(v^{\prime \prime }+\frac{1}{2})-3.56\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2\left\}\right\}$ SrO, blue bands: $\{\nu =24,702.81\mathrm{},+\{519.09(v^{\prime }+\frac{1}{2})-3.50\mathrm{}{(v^{\prime }+\frac{1}{2})}^2\left\}\right\}\{-\{653.47(v^{\prime \prime }+\frac{1}{2})-4.02\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2\left\}\right\}$ SrO, ultraviolet bands: $\{\nu =28,622.18\mathrm{},+\{497.81(v^{\prime }+\frac{1}{2})-5.97\mathrm{}{(v^{\prime }+\frac{1}{2})}^2\left\}\right\}\{-\{679.13(v^{\prime \prime }+\frac{1}{2})-9.13\mathrm{}{(v^{\prime \prime }+\frac{1}{2})}^2\}.\mathrm{}\}$

• Received 9 September 1932

DOI:https://doi.org/10.1103/PhysRev.42.609