Several cell designs have been systematically evaluated for gas flow entrainment and transport of laser ablated material to a secondary excitation source for elemental analysis. The best cell is not limited to samples of particular size or shape and is insensitive to sample surface irregularity. An annular gas sheath around the cell results in a transient response sufficiently fast to permit depth and lateral sampling of single samples or rapid throughput of different samples but slow enough to give a steady signal with laser repetition rates ≥10 Hz. Entrainment and transport of ablated particulates have been investigated experimentally and by model calculation for a test material (Mo metal). The equations for predicting diffusive and gravitational loss of particles in a horizontal tube are presented and discussed. The major loss mechanism appears to be gravitational deposition of relatively large particles formed during ablation and possibly by coalescence within the transfer tube. Entrainment of ablated Mo by the cell and mass transport from the cell to the secondary source were determined to be ∼90% and ∼40% efficient, respectively. Shot-to-shot fluctuation in particle size may cause corresponding variation in transport efficiency when the upper end of the ablated particle size distribution exceeds the size limit for particle transport.

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Partial Grotrlan diagrams and tables of relative Intensities with corresponding wavelengths of 102 Inductively coupled plasma (ICP) excited, nonresonant atomic bromine emission lines and 85 ICP excited, nonresonant atomic chlorine emission lines are presented for the air-path, photomultiplier-accessible region 3700-9900 A and 4200-9900 A, respectively. Several (ICP) excited lines of Ionized Br and Cl are listed. Vertical emission Intensity profiles of near-infrared Br I and Cl I lines are presented for an extended argon ICP torch. The present detection limit for both Br I and Cl I is 0.05 #tg for 8-µ . gas sampling loop Injections of HBr and Cl2 Into a low volume transfer line leading directly Into the ICP. The linear dynamic range for quantitative sampling loop analysis Is presently >5

Inductively coupled plasma (ICP) excitation of the 9212.91 Å nonresonant line of atomic sulfur is reported and is found to yield a detection limit more than 20-fold better than any visible or “air path” ultraviolet sulfur lines produced by the argon ICP. The ICP excited spectrum reported here for the element sulfur is markedly different from that reported for atmospheric pressure microwave-induced helium plasmas. Partial Grotrian diagrams and tables of relative intensities, detection limits, and corresponding wavelengths of 30 ICP excited, nonresonant atomic sulfur emission lines and 20 ICP excited, nonresonant atomic carbon lines are presented for the air path, photomultiplier accessible region 2000 to 9900 Å. No lines of ionized sulfur were observed in the 27-MHz, 1.75-kW argon ICP. Vertical emission intensity profiles of near infrared S(I) and C(I) lines are presented for both conventional and extended ICP torches. The present near infrared (S(I) 9212.91 Å and C(I) 9094.83 Å) detection limits for sulfur and carbon are 0.006 μg and 0.13 μg, respectively, using 8 μL gas sampling loop injections of H2S and CH4 into a low-volume transfer line leading directly into the ICP.

Preliminary qualitative multielemental inductively coupled plasma atomic spectra of C, H, N, and O are presented using a low dispersion, near infrared and red photodiode array spectrometer. Simple spectra of reasonable intensity are obtained with short (4 ms) integration times. Sensitivity and dispersion considerations are sharply contrasted with those conventionally associated with ultraviolet photodiode array spectra of metals in the inductively coupled plasma.