Penning Ionization Electron Spectroscopy in Glow Discharge:  Another Dimension for Gas Chromatography Detectors

Abstract

Admixtures to helium of 100 and 5 ppm of nitrogen, and 100 and 10 ppm of carbon monoxide were identified and measured in the helium discharge afterglow using an electrical probe placed into the plasma. For nitrogen and carbon monoxide gases, the measured electron energy spectra display distinct characteristic peaks (fingerprints). Location of the peaks on the energy scale is determined by the ionization energies of the analyte molecules. Nitrogen and carbon monoxide fingerprints were also observed in a binary mixture of these gases in helium, and the relative concentration of analytes has been predicted. The technically simple and durable method is considered a good candidate for a number of analytical applications, and in particular, in GC and for analytical flight instrumentation.

Collisional electron spectroscopy method for gas analysis

“…The sensor has large collecting area compared to the classical Langmuir probe -it is comparable to that of the anode. The plasma volume is reduced dramatically; it is about 0.02 -0.05 cm 3 , which is more than two orders of magnitude less, compared to the previous works [1][2][3]. The small size of the plasma volume permits a significant increase in the operating pressures.…”

“…It is based on identification of gas impurities by registration of groups of nonlocal fast electrons, released in reaction of Penning ionization of the impurity particles by helium metastable atoms. Further development of PLES method for identification of unknown species in a gas phase is reported in [3]. In [1-3] the nonlocal afterglow plasma of positive column at low pressures (0.5 -3.5 Torr) is used, and temporal resolution of the registration system is applied, which complicates the devices.…”

“…Further development of PLES method for identification of unknown species in a gas phase is reported in [3]. In [1][2][3] the nonlocal afterglow plasma of positive column at low pressures (0.5 -3.5 Torr) is used, and temporal resolution of the registration system is applied, which complicates the devices.…”

“…If the energy of penning electrons is p > w (where w is the potential between axis and discharge wall), these electrons reach the wall in a free diffusion. In the absence of electric field or when it has a small value (e.g., negative glow plasma, beam plasma), where T e , and hence e w are small, the energy spectrum of penning electrons represent sharp peaks near energies p , reproducing the spectrum R ) of reactions of type (1) [1][2][3]. Using the measured penning electrons spectra R( ) and the well known rate constants for Penning reactions one can identify the impurities and determine their concentrations.…”

Development of New Ionization Methods for GC/MS and LC/MS Interfaces

“…8) This method is based on the Penning ionization reaction (1) for He῍. The electron produced by reaction (1) has a kinetic energy E determined by…”