Fundamental characteristics and applications of an inductively-coupled plasma as an ion source for mass spectrometry

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5829428

Crain, J S

Noise power spectra of the {sup 85}Rb{sup +} signal and the {sup 93}Nb{sup +} signal from an inductively coupled plasma-mass spectrometer were compared to the noise power spectrum of Sr II emission from the plasma. Discrete frequency noise in the emission at the mass spectrometer sampling orifice was found to be nearly identical to that in the mass spectrometer signal. However, discrete frequency noise in emission from the plasma alone differed substantially in frequency from that in the mass spectrometer signal. The dependence of noise frequencies on plasma operating conditions was generally the same for the mass spectrometric measurements and both emission measurements. These results indicate that the plasma was the source of discrete frequency noise in the mass spectrometric signal. The major source of signal instability in this particular ICP-mass spectrometer was found to be 1/f noise. A new, home-made ICP-mass spectrometer was used to study the influence of Na, K, and U on ion signals from Y, Co, and As. In general, analyte signals were suppressed in the presence of excess matrix element. The extent of suppression was greatest for the element with high ionization energy (As) and least for the element with the smallest ionization energy (Y). These trends in the interference effect could be altered by applying a positive voltage to the first element of the ion optics. When the skimmer orifice diameter was made smaller than the sampling orifice diameter, analyte signal suppression was uniform and more extensive. Under these conditions, the heavy matrix element (U) induced more suppression than did the light matrix element (Na). Degrees of ionization for As and Sb in an inductively coupled plasma were measured using mass spectrometry, and electron density (n{sub e}) in the plasma just upstream of the mass spectrometer sampling orifice was measured from Stark broadening of the H I 486.13 nm emission line.

• Research Organization: Iowa State Univ. of Science and Technology, Ames, IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5829428
• Country of Publication: United States
• Language: English

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47 OTHER INSTRUMENTATION
640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ACTINIDES
ALKALI METALS
ANTIMONY
ARSENIC
COBALT
ELECTRON DENSITY
ELEMENTS
ION SOURCES
ION TEMPERATURE
IONIZATION
MASS SPECTROMETERS
MEASURING INSTRUMENTS
METALS
NOISE
PLASMA
POTASSIUM
SEMIMETALS
SIGNALS
SODIUM
SPECTROMETERS
STARK EFFECT
TRANSITION ELEMENTS
URANIUM
USES
YTTRIUM