Laser-based secondary neutral mass spectroscopy: Useful yield and sensitivity Page: 1 of 32
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Invited Paper -
Proceedings for IISC-6 at Argonne National Laboratory on August 25-29, 1986
LASER-BASED SECONDARY NEUTRAL MASS
SPECTROSCOPY: USEFUL YIELD AND SENSITIVITY*
C. E. Young, M. J. Pellin, W. F. Calaway, ? ! I
B. Jorgensen,** E. L. Schweitzer, and D. M. Gruen
CONF-860807-4 Materials Science and Chemistry Divisions JUL
DE87 011464 Argonne National Laboratory
Argonne, IL 60439
Multiphoton ionization (MPI) by pulsed, tunable lasers provides a
sensitive means for detection of neutral atoms due to the high efficiency
achievable both in the ionization and subsequent detection. Substantial
selectivity can be achieved by excitation between energy levels of the atom of
interest. This resonant MPI technique can access all atomic states of any
particular atom including its ground and metastable levels. In principle all
elements may be ionized through judicious selection of the color of the
excitation laser light. In practice resonance ionization has been
experimentally demonstrated for nearly every element .
A variety of problems exist in order to optimally apply resonance
ionization spectroscopy (RIS) to the detection of sputtered neutral atoms,
however. Several of these problems and their solutions are examined in this
paper. First, the possible useful yields obtainable and the dependence of
useful yield on various laser parameters for this type of sputtered neutral mass
spectrometer (SNMS) are considered. Second, the choice of a mass
spectrometer and its effect on the instrumental useful yield is explored in light
of the unique ionization region for laser based SNMS. Finally a brief
description of noise sources and their effect on the instrumental sensitivity is
That it is possible to combine in one instrument both high useful yields
and high sensitivity for the detection of minority species (either very dilute
surface constituents or species sputtered in highly excited states) will be
demonstated with results on Fe implanted Si samples in the surface analysis
by resonant ionization of sputtered atoms (SARISA) instrument. SARISA
acomplishes the necessary noise reduction without signal loss through the
extraction of the photoions into a sector-field time-of-flight (TOF) mass
spectrometer. In standard, isochronous operation, energy and angular
spreads at the point of ionization are compensated in flight to produce well-
resolved TOF mass spectra. Noise sources (photons, metastable and
scattered atoms) escaping through transparent grids are strongly suppressed.
*Work supported by the U.S. Department of Energy, BES-Materials Science,
under Contract W-31-109-ENG-38.
**Fysisk Institut, Odense Universitet, Denmark.
The submitted manuscript has been authored
A ac o fte .Gr 3-1ly, the U. S. Government retains
noneclosive royaltyfree license to publish
er rpouce elhe published farm of this
cntr on Or alo others to do so f for
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Young, C.E.; Pellin, M.J.; Calaway, W.F.; Joergensen, B.; Schweitzer, E.L. & Gruen, D.M. Laser-based secondary neutral mass spectroscopy: Useful yield and sensitivity, article, January 1, 1986; United States. (https://digital.library.unt.edu/ark:/67531/metadc1113129/m1/1/: accessed March 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.