Q-SWITCHED LASER ENERGY ABSORPTION IN PLUME OF AN ALUMINUM ALLOY

Time-and spatially-resolved spectrometric observations were made of single and multiple spike, Q-switched laser plumes that are to be used for analytical procedures. The observations suggest the rapid formation of an atmospheric plasma initially containing little sample material. The resulting intense continuum background radiation which is present in time-integrated spectra lasts for only a few tenths of a μsecond during and after each laser spike and can be separated in time from characteristic line emissions which last many μseconds. Measurements indicate that a large fraction of the energy in each spike of a laser pulse is absorbed by the plume at some distance from the surface of the target and, therefore, does not reach the target to cause direct vaporization. Observations of the craters and spectra suggest that the hot plume continues to cause sample vaporization after the laser pulse is over. © 1969, American Chemical Society. All rights reserved.