Applied Spectroscopy

Birks, L. S.

doi: 10.1366/000370269774380608pmid: N/A

Calculation methods for quantitative analysis, energy dispersion, and inhomogeneous samples are current areas in x-ray analysis which offer hope of reducing analysis costs. Other areas which extend the capabilities of x-ray analysis include improved analyzer crystals, diffraction gratings, and effects of valence on spectral lines. Electron spectrometry promises to be a valuable technique for low atomic number elements.

Strock, Lester W.

doi: 10.1366/000370269774380644pmid: N/A

Walters, J. P.

doi: 10.1366/000370269774380662pmid: N/A

Major developments in the understanding of the physics and chemistry of the atmospheric pressure spark discharge are presented and commented upon. These include work in the areas of equipment, initial gap breakdown, spark channel formation, electrode sampling phenomena, sample propagation phenomena, excited state production, related plasma physics, and counter electrode phenomena.

Hirschmann, R. P.; Harnish, D. F.; Holmes, J. R.; MacKenzie, J. S.; Fox, W. B.

doi: 10.1366/000370269774380617pmid: N/A

The infrared spectra of trifluoroamine oxide and its 15N analogue have been measured from 4000 to 260 cm−1. Fundamental frequency assignments (based upon C3ν symmetry) made from the 14N spectrum are: ν1(a1) = 1689, ν2(a1) = 740, ν3(a1) = 528, ν4(e) = 880, and ν6(e) = 398 cm−1. Normal coordinate calculations support the assignment of the remaining fundamental ν5(e) to a band system appearing as a shoulder, about 558 cm−1, on the intense ν3(a1) fundamental.

Weidner, James P.; Block, Seymour S.

doi: 10.1366/000370269774380653pmid: N/A

The infrared spectra of 15 aliphatic and aromatic zinc sulfinates are given. With zinc p-toluene-sulfinate, run neat as an extremely thin, flat crystal, the symmetric and asymmetric S → 0 peaks were clearly visible at 10.1 μ (990 cm−1) and 10.6 μ (943 cm−1), respectively, and similar absorptions were obtained for the other sulfinates run as Nujol mulls. In distinction to sulfonic acid salts, the sulfinates have practically no absorption in the 8–9 μ (1250–1110 cm−1) region, whereas the sulfonates have no absorption in the 10–11 μ (1000–910 cm−1) thus indicating the analytical value of the spectra in distinguishing these two groups of compounds.

Vierling, J.; Gilfrich, J. V.; Birks, L. S.

doi: 10.1366/000370269774380716pmid: N/A

The integral reflection coefficient R was measured for the (200) planes in LiF using a double crystal spectrometer over the wavelength range 0.7–2.1 Å. For cleaved LiF, R was about 0.7 × 10−4 rads compared to 0.3 × 10−4 calculated for the theoretically perfect crystal case. After abrading with 1.5–20 μ carborundum, R increased to 2.90 × 10−4 at the 0.7-Å end of the range and to 3.68 × 10−4 at the 2.1-Å end. For a flexed and reflattened crystal, R increased further to 9.45X10−4 at the 0.7-Å end of the range but was not improved over the abraded crystal at the 2.1-Å end. Theoretical R values for mosaic graphite were compared with LiF. The value for graphite at 1.66 Å was 4.5 times higher than that calculated for mosaic LiF and 1.3 times higher than the measured graphite values of Gould, Bates, and Sparks. It appears that one can approximate theoretical mosaic crystals by either distorting a nearly perfect crystal such as LiF or by orienting powder crystallites as in the case of graphite.

Batt, A.

doi: 10.1366/000370269774380635pmid: N/A

The use of a fundamental parameter method for effecting matrix corrections in quantitative x-ray spectrochemical analysis is described. A versatile computer program calculates composition directly from measured intensities. Variations in the basic approach are employed in the analysis of a series of sulfide and oxide samples. The Applied Research Laboratories multi-channel x-ray quantometer (MXQ) is briefly described.

Morrison, G. H.; Skogerboe, R. K.; Bedrosian, A. J.; Rothenberg, A. M.

doi: 10.1366/000370269774380743pmid: N/A

The advantages that can be realized through the use of a high current dc arc for the emission spectrographic analysis of ashed biological materials are presented. The method described utilizes 5–10 mg of ash per analysis and provides detection limits between 1 and 50 parts per billion (on the original dry weight basis) for a large number of elements. The precision estimates of the method, based on four replicate analyses, are generally better than ±20% and comparative analyses suggest that the accuracies are within these limits. Data is presented which supports the possibility of using a single analytical curve for several different types of ashed biological materials.

Harrison, Merle; Andre, Charles

doi: 10.1366/000370269774380707pmid: N/A

A modified digestion mixture utilizing sodium molybdate as a catalyst is described for plant materials. In atomic absorption spectroscopy, special attention is given to calcium analyses using this mixture, because of various interfering ions. The digestion mixture is suitable for numerous other cation determinations. Also, a method of increasing the sensitivity for copper by adding methanol is described.

Shifrin, N.; Rarmírez-Muñoz, J.

doi: 10.1366/000370269774380671pmid: N/A

A study is presented on the influence of the instrumental time constant value in the determination of fluctuational sensitivity in atomic-absorption flame photometry. Fluctuational concentration limit (detection limit) has been defined as a function of the noise level of the blank reading (blank adjusted at the 0% absorption level), while the signal noise is a direct function of the time constant of the readout system employed. Employing a Beckman 979 atomic-absorption system and recorder, a scale expander unit was modified to provide a time constant control. The behavior of several elements is presented as an example of the dependence of the fluctuational concentration limit on the system time constant. These results, clearly indicating a basic relationship, lead to the establishment and presentation of a new criterion in an attempt to define and to compare concentration limits of a fluctuational nature.