Direct ppb measurement of Airborne Molecular Contaminations (AMC)
Approved IMS technology
Non-radioactive ionization by stable electron beam
No X-ray licensing required
Fast response and cleardown
No interference from acid gases and halogens
Continuous, unattended monitoring
Optional multipoint sampling
The ion mobility spectrometer E-NIMS is an advanced analytical device for fast and reliable trace detection of volatile
compounds in industrial environments. E-NIMS combines state-of-the-art ion mobility spectrometry with an innovative
non-radioactive ionisation technology. A special tailored electron beam source offering high stability, pulsed mode
operation and intensity control allows efficient ionization and outstanding performance. With the E-NIMS, elaborate
licensing, regulatory supervision and disposal of radio-active material, as it is neccessaray for most conventional
ion mobility devices, belongs to the past. The E-NIMS opens up new areas of applications.
Continuous emission monitoring of ammonia (NH3) in ambient air
Ion mobility spectrometry (IMS) represents a widely accepted and established analytical technique in many applications.
In ion mobility spectrometry characteristic drift velocities of ionized molecules (cations or anions) in an electrical
field at atmospheric pressure are determined. Separation of the ions according to mass and size, followed by their detection
at a Faraday cup and amplification of the ion current yields typical IM spectra. From the drift time and intensity of the
signals both qualitative and quantitative analytical information are obtained.
With IMS-devices a direct measurement of volatile compounds in ambient air within a few seconds is possible without an
elaborate sample preparation, so no reagents or other consumables are required for operation. A very sensitive detection
in the ppb to ppt range is achieved. The selectivity of detection depends on the proton or electron affinity of the analytes
and may be increased using specific dopant compounds. In our system sampling is realized via a sample loop for continuous
sampling with fast response and cleardown.
Due to the advantages of IMS in general and the specific features of the non-radioactive ionization source E-Ray, E-NIMS
is ideally suited for a sensitive and continuous on-line detection of volatile industrial compounds in industrial environments.
E-NIMS is especially designed for the detection of airborne molecular contamination (AMC) e.g. in semiconuctor industries,
and optimized for the detection of specific substances. E-NIMS-NH3 is adapted for ammonia quantification, it provides a
detection limit of 2 ppb and a detection range up to 50 ppb.
On request, further molecular bases (amines, NMP), molecular acids and halogens can be determined.
The E-NIMS employs a novel and innovative non-radioactive ionization source for IMS called E-Ray.
A cathod ray tube delivers electrons with an energy of 12 keV, which pass out through a thin but stable and inert ceramic membrane.
The electrons are scattered and stopped in the atmosphere forming a small and well defined spherical ionization volume of approx.
1 mm diameter.
The emitted electrons have a kinetic energy com-parable to the electron energy of b-sources (3H, 63Ni) common in conventional
IMS. So the E-Ray source leads to the same well-understood ionization mechanisms and offers following further improved analytical
The E-Ray generates a high electron current (max. 10 µA), which exceeds the intensity of typical b-sources (100 Mbq ~ 60 pA)
by several orders of magnitude. As result an outstanding sensitivity of the E-NIMS is obtained. Moreover the intensity of the
electron source can be adjusted leading to an enhanced dynamic range.
The source is not subject to any degradation processes, so it provides a stability which is comparable to common radioactive
sources and unique for non-radioactive sources. Thus a high repeatablity of the analytical results is achieved.
Gas samples are taken from a port at the rear side by an internal pump via a sample loop. Sampling tubes (recommended PFA or
PTFE, max. length = 50m) are connected directly or via an optional multiplexer to the sample port using standard 6 mm connectors.
Due to the sample loop, memory effects are minimized. The sampling occurs once a minute. Within 15 s IMS data are aquired with 5 Hz
using an ultra-low noise current amplifier. The analyte concentration is calculated from this complete dataset. This allows a
continuous monitoring with a one-minute temporal resolution and a high reliability.
The device is operated at elevated temperature, fast response and cleardown times as well as a short start-up time (60 min)
are obtained even for analytes like ammonia.
Ammonia and other AMC are ionized via continuously added and primary ionized dopant molecules. Dopant and analyte signals
are completely separated and the influence of varying environmental conditions is minimized. E-NIMS is equipped with an
internal calibration. The software includes a calibration routine offering a simple and fast two point calibration of
the device using an internal standard.