Ma. Shannon et al., LASER-ABLATION MASS REMOVAL VERSUS INCIDENT POWER-DENSITY DURING SOLID SAMPLING FOR INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROSCOPY, Analytical chemistry, 67(24), 1995, pp. 4522-4529
For laser ablation solid sampling, the quantity of material ablated (r
emoved) influences the sensitivity of chemical analysis. The mass remo
val rate depends strongly on the laser power density, which is the mai
n controllable parameter for a given material and wavelength parameter
using laser solid sampling for inductively coupled plasma atomic emis
sion spectroscopy (ICP-AES). For a wide variety of materials, a decrea
se in the rate of change, or roll-off, in mass removed is observed wit
h increasing incident laser power density, The roll-off results from a
change in the efficiency of material removed by the laser beam, prima
rily due to shielding of the target from the incident laser energy by
a laser-vapor plume interaction, Several analytical technologies were
employed to study the quantity of mass removed versus laser power dens
ity, Data for mass ablation behavior versus laser power density are re
ported using ICP-AES, atomic emission from a laser-induced plasma near
the sample surface, acoustic stress power in the target, and measurem
ents of crater volumes, This research demonstrates that the change in
ICP-AES intensity with laser power density is due to changes in the ma
ss removal, The roll-off in mass ablation is not due to a change in pa
rticle size distribution of the ablated species, fractionation of the
sample, or a change in transport efficiency to the ICP torch, Accurate
tracking of the ICP-AES with the laser ablation process justifies the
use of internal and external standardization.