Byron A. Palmer

Temperature determinations in the inductively coupled plasma using a Fourier transform spectrometer

Abstract A vertical profile of iron I excitation temperature in the inductively coupled plasma was determined using spectroscopic techniques based on the Einstein-Boltzmann expression for spectral line intensity and the powerful information gathering ability of a high resolution Fourier transform spectrometer. Calculated temperature values were found to be critically dependent on the oscillator strength values chosen from the literature; however, a qualitative picture of the vertical excitation temperature gradient in the plasma was well-defined and was found to reach a maximum value in the normal analytical zone of the plasma. Excitation temperatures for iron I, nickel I, cobalt I, and vanadium I and II in the normal analytical zone of the plasma were also determined by the same method.

Line width and line shape analysis in the inductively coupled plasma by high resolution Fourier transform spectrometry

Abstract High resolution Fourier transform spectrometry has been used to perform line width and line shape analysis of 81 Fe I emission lines in the spectral range 290–390 nm originating in the normal analytical zone of an inductively coupled plasma. Computer programs using non-linear least squares fitting techniques for line shape analysis were applied to the fully resolved spectra to determine Gaussian and Lorentzian components of the total observed line width. The Gaussian component was found to be the predominant effect, but the Lorentzian component was found to also contribute significantly. The effect of noise in the spectrum on the accuracy of the line fitting technique was assessed, and the importance of signal-to-noise ratio for accurate line shape analysis is demonstrated and discussed. Translational (Doppler) temperatures calculated from the Gaussian components of 81 lines were found to be 6310K with a relative standard deviation of 217K.

Atlas for optogalvanic wavelength calibration

The accuracy of laser wavelength calibration was demonstrated using a uranium hollow cathode discharge tube. (AIP)

Transition probability and collision broadening of the 1.3-μm transition of atomic iodine

We have made direct absorption measurements of the transition probability and collision broadening of the 1.3-μm 2P1/2 → 2P3/2 transition of atomic iodine. Atomic iodine was generated in heated iodine vapor, and the spectrum was obtained with a Fourier-transform spectrometer. A transition probability was measured that corresponds to a 2P1/2 radiative lifetime of 125 msec. Broadening coefficients of 1.4, 1.7, 3.1, and 1.3 MHz/Torr at 1000 K were found for argon, oxygen, molecular iodine, and atomic iodine, respectively. The intensity of the (2, 4) forbidden electric-quadrupole line was measured and yielded the ratio of electric-quadrupole to magnetic-dipole transition probability of 2.7 × 10−3. Molecular absorption spectra of IO and SiI were seen in high-temperature spectra of a quartz cell containing an I2/O2 mixture.

Precision isotope shifts for the heavy elements. I. Neutral uranium in the visible and near infrared

A Fourier transform spectrometer was used to obtain high-resolution spectra of a 234UI4/238UI4 electrodeless discharge lamp. Over 2000 uranium isotope shifts were measured in the visible and near-infrared regions. Level isotope shifts were determined by least squares for 183 odd and 518 even levels of U i with an overall standard deviation of 0.0036 cm−1.

Rotational temperatures of argon-nitrogen ICP discharges measured by high-resolution Fourier transform spectrometry

Abstract The intensity distribution in the rotational structure of the electronic band B 2 Σ + g → X 2 Σ + g of N + 2 (0,0) was measured by high-resolution Fourier transform spectrometry. This spectral information enabled estimates of the rotational temperatures in atmospheric-pressure argon-nitrogen inductively coupled plasmas (Ar-N 2 ICPs). These rotational temperatures were compared to the excitation and the Doppler temperatures of Ar ICP and Ar-N 2 ICPs having from 0 to 100% nitrogen in the outer gas flow. The rotational temperature of the mixed-gas plasmas ranged from 5500 to 10000 K, depending on the percentage of nitrogen in the outer gas flow, compared to 7800 K for the Ar ICP. The lowest and the highest rotational temperatures were obtained when the outer gas flow contained 100% and 17% nitrogen, respectively.

Line widths and temperatures of Ar-N2 ICP discharges measured by high-resolution Fourier transform spectrometry

Abstract The high-resolution Fourier transform spectrometer (FTS) of the Los Alamos National Laboratory was used for diagnostic studies of Ar-N 2 ICP discharges. High-resolution FTS data were obtained to: (a) conduct analysis of line widths and line shapes for Fe lines to ascertain contributions from the Gaussian and Lorentzian components; (b) to calculate the Doppler or translational temperatures of emitting species by using the half width of the Gaussian component; and (c) to determine excitation temperatures based on the relative intensities of many spectral lines. The effect of gas composition and plasma operating conditions on line widths, Doppler and excitation temperatures were examined.

Energy levels and isotope shifts for singly ionized uranium (U ii)

New uranium hollow-cathode Fourier-transform spectra have been recorded between 1800 and 42 000 cm−1. Combined with earlier visible and ultraviolet spectra, these have led to 354 odd levels and 809 even levels of singly ionized uranium (U ii) belonging to four odd and six even configurations. High-resolution Fourier-transform spectra of an electrodeless discharge lamp containing 238UI4 and 234UI4 were used to measure splittings of more than 800 isotopic U ii doublets to an accuracy of ~0.001 cm−1. From these transition isotope shifts 114 odd- and 397 even-level isotope shifts were determined.

Observation of line shifts and line profiles in an inductively coupled argon plasma

Abstract Shifts in spectral line positions of argon, iron, barium, calcium and strontium are addressed in this preliminary study of the effect of pressure, and electron density on wavenumber position in the 27.12 MHz inductively coupled plasma (ICP). We report line shifts for three sets of data in an argon ICP. The first set of data shows the effect of power (1.1, 1.5, 1.9 kW) on shifts of argon (21 lines) and iron (28 lines) lines in the ultraviolet and visible. The second set of data gives shifts of 25 Ar lines in the near infrared (i.r.) and far visible at 1.1 kW. The third set of data concerns prominent ion lines of calcium, barium and strontium. Commercial hollow cathode lamps (HCL) were used to obtain unshifted line positions. The Los Alamos Fourier Transform Spectrometer was used to obtain the data.

Hyperfine structure and isotope shift of the 1.3-μm transition of 129 l

High resolution Fourier transform spectra of the 1.3-microm emission from (127)I and (129)I electrodeless discharge lamps are presented and analyzed. The hyperfine splitting constants of (129)I are: A = 18.35 +/- 0.01 mK and B = 26.55 +/- 0.07 mK for the J = 3/2 ground state and A = 146.32 +/- 0.02 mK for the J = (1/2) excited state. The validity of the theoretical intensity and isotope relationships is confirmed. The isotope shift between (129)I and (127)I for the 1.3-microm transition was measured to be <1 mK.