The photoabsorption cross-sections of magnesium, calcium, strontium, and zinc were measured in the vacuum ultraviolet region by using either the synchrotron radiation source in Hsinchu, Taiwan, Republic of China or a discharge lamp as a continuum background source. Samples were confined within a heatpipe oven, and the atom number densities were determined by the temperature profile distributed along the heatpipe. The relative cross-sectons of the measured autoionization series were in agreement with those reported for thermionic diode measurements, except for certain spectral details. The cross sections at corresponding ionization thresholds were 2.3, 1.2, 4.5, and 0.5 Mb for magnesium, calcium, strontium, and zinc, respectively.
