Self-focused electron beams produced by pyroelectric crystals on heating or cooling in dilute gases

Brownridge, James D.; Shafroth, S. M.

doi:10.1063/1.1418458

Cited by 80 publications

(50 citation statements)

References 10 publications

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“…Brownridge published results showing the fluorescence of the K-shell lines of gold ͑Z =79͒, 6 and later was able to fluoresce lead ͑Z =82͒, although those results are not yet published. 7 The positive results pertaining to the increase in the maximum x-ray energy by using paired crystals led us to attempt to reproduce Brownridge's results, and then to fluoresce materials with higher atomic number than lead.…”

Section: Fluorescence Of Heavy Metalsmentioning

confidence: 92%

High-energy x-ray production with pyroelectric crystals

Geuther

Danon

2005

Journal of Applied Physics

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The invention of pyroelectric x-ray generator technology has enabled researchers to develop ultraportable, low-power x-ray sources for use in imaging, materials analysis, and other applications. For many applications, the usefulness of an x-ray source is determined by its yield and endpoint energy. In x-ray fluorescence, for example, high-energy sources enable the excitation of the K-shell x-ray peaks for high-Z materials as well as the lower-energy L-shell peaks, allowing more positive sample identification. This report shows how a paired-crystal pyroelectric source can be used to approximately double the endpoint x-ray energy, in addition to doubling the x-ray yield, versus a single-crystal source. As an example of the advantage of a paired-crystal system, we present a spectrum showing the fluorescence of the K shell of thorium using a pyroelectric source, as well as a spectrum showing the fluorescence of the K shell of lead. Also shown is an x-ray spectrum with an endpoint energy of 215 keV.

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Section: Fluorescence Of Heavy Metalsmentioning

confidence: 92%

High-energy x-ray production with pyroelectric crystals

Geuther

Danon

2005

Journal of Applied Physics

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“…A mechanism of ionization involving a form of atmospheric pressure chemical ionization is proposed, whereby molecules that are detected as protonated species have undergone reaction with reactant ions present in humid air of the form ϩ H(H 2 O) n or Ϫ OH(H 2 O) n . Previous work by others on pyroelectric materials has revealed the production of ions and electrons from pyroelectric crystals [7][8][9][10][11][12][13][14][15] as well as field ionization of deuterium gas to form D ϩ , which is used in pyroelectric fusion experiments [16,17]. None of these studies involve ionization at ambient pressure as the chief mode of ionization.…”

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confidence: 99%

Ionization mechanism of the ambient pressure pyroelectric ion source (APPIS) and its applications to chemical nerve agent detection

Neidholdt

Beauchamp

2009

J. Am. Soc. Mass Spectrom.

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We present studies of the ionization mechanism operative in the ambient pressure pyroelectric ionization source (APPIS), along with applications that include detection of simulants for chemical nerve agents. It is found that ionization by APPIS occurs in the gas-phase. As the crystal is thermally cycled over a narrow temperature range, electrical discharges near the surface of the crystal produce energetic species which, through reactions with atmospheric molecules, result in reactant ions such as protonated water clusters or clusters of hydroxide and water. Reactant ions can be observed directly in the mass spectrometer. These go on to react with trace neutrals via proton transfer reactions to produce the ions observed in mass spectra, which are usually singly protonated or deprotonated species. Further implicating gas-phase ionization, observed product distributions are highly dependent on the composition of ambient gases, especially the concentration of water vapor and oxygen surrounding the source. For example, basic species such as triethylamine are observed as singly protonated cations at a water partial pressure of 10 torr. At a water pressure of 4 torr, reactive oxygen species are formed and lead to observation of protonated amine oxides. The ability of the APPIS source to detect basic molecules with high proton affinities makes it highly suited for the detection of chemical nerve agents. We demonstrate this application using simulants corresponding to VX and GA (Tabun). With the present source configuration pyridine is detected readily at a concentration of 4 ppm, indicating ultimate sensitivity in the high ppb range. (J Am Soc

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“…Whereas in the gap -Z face side, the drift of species (electrons/+ions) is effectuated in opposite directions. From such scenarios the electron emission could be measured only from -Z face and during cooling [9,14,15].…”

Section: Figmentioning

confidence: 99%

“…Responsivity of the photodiode is about 0.2 A/W for electrons with energy in the range of 1 to 40 keV. Electrons produced by LN crystals have a large energy up to 100 keV [2,9], and hence the PD amplification factor of the emission current is about 10 4 [10]. Receptive electron-beam-resist (ZEP-520, Nippon Zeon Co., Ltd.) was used to study the spatial distribution of the electron current.…”

Section: Introductionmentioning

confidence: 99%

Pyroelectric electron emission from −Z face polar surface of lithium niobate monodomain single crystal

et al. 2006

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Pyroelectric electron emission current measurements and spatial electron current distribution collections were investigated from -Z face polar surface of lithium niobate monodomain crystals.The electron emission was detected during cooling due to a field ionization effect. The gap distance variation between the crystal surface and the electron collector significantly influenced the emission behavior. For small gaps (<2 mm) the emission was controlled by intermittent runway ionizations (screening of charge species (electrons and +ions) from plasma breakdown). Whereas, for large gaps (>2 mm) the pyroelectric electron emission was supplied from a soft and maintained plasma medium formation.

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Self-focused electron beams produced by pyroelectric crystals on heating or cooling in dilute gases

Cited by 80 publications

References 10 publications

High-energy x-ray production with pyroelectric crystals

High-energy x-ray production with pyroelectric crystals

Ionization mechanism of the ambient pressure pyroelectric ion source (APPIS) and its applications to chemical nerve agent detection

Pyroelectric electron emission from −Z face polar surface of lithium niobate monodomain single crystal

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