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New Type of Plasma-Source Mass Spectrometer Utilizing Simultaneous Detection for the Trace Elemental Analysis of Micron-Sized Volumes of Materials or Liquids

IP.com Disclosure Number: IPCOM000111185D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Arrowsmith, P: AUTHOR [+2]

Abstract

Disclosed is a device which uses a high temperature plasma ion source, a Mattauch-Herzog mass spectrometer, and a multi-channel ion detector for trace elemental analysis of solids or liquids. Ions are sampled from the atmospheric plasma and transported through four stages of differential pumping into the mass spectrometer with ion optics that are self-aligned to the sampling orifice and the mass spectrometer entrance slit.

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This is the abbreviated version, containing approximately 52% of the total text.

New Type of Plasma-Source Mass Spectrometer Utilizing Simultaneous
Detection for the Trace Elemental Analysis of Micron-Sized Volumes
of Materials or Liquids

      Disclosed is a device which uses a high temperature plasma ion
source, a Mattauch-Herzog mass spectrometer, and a multi-channel ion
detector for trace elemental analysis of solids or liquids.  Ions are
sampled from the atmospheric plasma and transported through four
stages of differential pumping into the mass spectrometer with ion
optics that are self-aligned to the sampling orifice and the mass
spectrometer entrance slit.

      A challenge often encountered in materials applications is the
need for elemental analysis of contaminant particles or inclusions in
various materials.  One technique that has sufficient sensitivity and
is capable of semi-quantitative analysis is Inductively Coupled

Plasma (ICP) mass spectrometry coupled with laser ablation sample
introduction [1].  Compositional analysis of a small volume of
material or an inclusion by the ablation technique requires a single
laser pulse, to avoid sampling the surrounding material.  The
resulting signal is in the form of a transient and the currently
available sequential plasma-source mass spectrometers are too slow to
detect more than a small fraction of the ions in the short time
available.  Hence, these instruments are limited in the number of
elements that can be determined.

      A schematic of an instrument designed to overcome such problems
is shown in the figure.  In this device sampled material is
introduced into the center of a plasma which is generated by
inductively coupling RF power into a rare gas (He or Ar).  The plasma
efficiently atomizes and ionizes the material.  The plasma is sampled
by a cone orifice on the vacuum chamber.  The resulting expansion is
skimmed by a second cone orifice (located inside the shock-front of
the supersonic gas expansion) which serves as the conductance limit
between the first two stages of differential pumping.  The ions are
then accelerated through an electrically biased, third cone o...