+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Knudsen cell mass spectrometry using restricted molecular beam collimation. I. Optimization of the beam from the vaporizing surface



Knudsen cell mass spectrometry using restricted molecular beam collimation. I. Optimization of the beam from the vaporizing surface



Rapid Communications in Mass Spectrometry 29(1): 10-18



This study analyzes molecular beam sampling by mass spectrometry by the Knudsen method using the so-called " restricted collimation device" . This device, defined by the field and source apertures, was proposed in order to eliminate any additional contribution to the genuine molecular beam of surface vaporizations coming from the vicinity of the effusion orifice as usually detected by the ion source of a mass spectrometer. The molecular transmission of the " restricted collimation device" was calculated using a vaporization law under vacuum taking into account the real surface where the molecules are emitted, i.e., the sample evaporation surface in the Knudsen cell or the effusion orifice section, towards the ion source inlet by integration of elementary solid angles. An optimum is observed depending on the pair of selected apertures that define the restricted collimation device, i.e., the field and source apertures. This optimum is different from that previously calculated when taking into account only the solid angle, as defined by the restricted collimation device. This difference is attributed to the previously approximate assumption that optimizing the restricted collimation solid angle automatically optimizes the sampling of the effused beam included in the restricted collimation angle. Moreover, the location of the evaporating surface for molecules traveling through the collimation device towards the ionization chamber remains an important factor: the distance between the sample evaporation surface and the field aperture is of paramount importance as it changes the molecular transmission to the mass spectrometer or to any target collection device in the conventional Knudsen method.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 058190131

Download citation: RISBibTeXText

PMID: 25462358

DOI: 10.1002/rcm.7071


Related references

Effusive molecular beam-sampled Knudsen flow reactor coupled to vacuum ultraviolet single photon ionization mass spectrometry using an external free radical source. Review of Scientific Instruments 84(11): 114104, 2013

An evaluation of lesion detectability with cone beam, fan beam and parallel beam collimation in SPECT by continuous ROC analysis. Journal of Nuclear Medicine 34(5 Suppl. ): 81P, 1993

Electron beam alignment and beam collimation in a dual beam betatron. Physics in Medicine and Biology 14(2): 340, 1969

Zevalin and BEAM (Z-BEAM) versus rituximab and BEAM (R-BEAM) conditioning chemotherapy prior to autologous stem cell transplantation in patients with mantle cell lymphoma. Hematological Oncology 34(3): 133-139, 2016

Particle selection and beam collimation system for laser-accelerated proton beam therapy. Medical Physics 32(3): 794-806, 2005

Coherent beam-beam tune shift of unsymmetrical beam-beam interactions with large beam-beam parameter. Physical Review. E Statistical Nonlinear and Soft Matter Physics 71(3 Pt 2b): 036501, 2005

Cardiac SPECT using combined cone-beam and fan-beam collimation. Journal of Nuclear Medicine 44(5 Suppl.): 63P, 2003

An evaluation of lesion detectability with cone-beam, fanbeam and parallel-beam collimation in SPECT by continuous ROC study. Journal of Nuclear Medicine 35(1): 135-140, 1994

Optimization of a three slit collimation system for a SAXS camera with a divergent beam. Journal of X-Ray Science and Technology 20(3): 331-338, 2012

Molecular-beam mass spectrometry of van der Waals clusters. Mass spectrum of hydrogen sulfide dimer. Russian Chemical Bulletin 44(5): 813-818, 1995

Beam characteristics and clinical possibilities of a new compact treatment unit design combining narrow pencil beam scanning and segmental multileaf collimation. Medical Physics 25(12): 2358-2369, 1998

Characterization of electron beam generated transformation products of Irganox 1010 by particle beam liquid chromatography-mass spectrometry with on-line diode array detection. Journal of Chromatography A 679(2): 285-297, 1994

Study of amino acids by means of liquid chromatography mass spectrometry: Optimization of the particle-beam interface. Analytica Chimica Acta 401(1-2): 55-64, 1999

Identification by particle-beam liquid chromatography-mass spectrometry of transformation products of the antioxidant Irganox 1330 in food-contact polymers subjected to electron-beam irradiation. Journal Of Chromatography. 629(2): 283-290, 1993

Optimization of the Hewlett-Packard particle-beam liquid chromatography-mass spectrometry interface by statistical experimental design. Journal of the American Society for Mass Spectrometry 6(6): 507-512, 1995