Ionization on Platinum and Tungsten Surfaces. I. The Alkali Metals

Datz, S.; Taylor, Ellison H.

doi:10.1063/1.1742931

Cited by 183 publications

(21 citation statements)

References 14 publications

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“…Generally, surface ionization is not desired in AMS measurements due to the very intense signals which can be generated by this process and which are not well quantifiable (Allan et al, 2003). In equilibrium, the ratio of the number of potassium ions (n + ) to the number of potassium atoms (n a ) vaporizing from a tungsten surface is a function of the surface temperature T , the work function of tungsten, and the ionization potential of potassium and is described by the Saha-Langmuir equation (Datz and Taylor, 1956),…”

Section: Chemical Reactions With the Vaporizermentioning

confidence: 99%

“…This change over the course of the day suggests that the vaporizer history has an important influence on the efficiency of surface ionization. Apparently the adsorption of chlorine atoms at the vaporizer surface over the day caused an increase in work function for the tungsten surface (Jowett and Hopkins, 1970), associated with an increase in surface ionization efficiency (Datz and Taylor, 1956). …”

Section: F Drewnick Et Al: Particle-vaporizer Interactions and Theimentioning

confidence: 99%

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Aerosol mass spectrometry: particle–vaporizer interactions and their consequences for the measurements

et al. 2015

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Abstract. The Aerodyne aerosol mass spectrometer (AMS) is a frequently used instrument for on-line measurement of the ambient sub-micron aerosol composition. With the help of calibrations and a number of assumptions on the flash vaporization and electron impact ionization processes, this instrument provides robust quantitative information on various non-refractory ambient aerosol components. However, when measuring close to certain anthropogenic or marine sources of semi-refractory aerosols, several of these assumptions may not be met and measurement results might easily be incorrectly interpreted if not carefully analyzed for unique ions, isotope patterns, and potential slow vaporization associated with semi-refractory species.Here we discuss various aspects of the interaction of aerosol particles with the AMS tungsten vaporizer and the consequences for the measurement results: semi-refractory components -i.e., components that vaporize but do not flashvaporize at the vaporizer and ionizer temperatures, like metal halides (e.g., chlorides, bromides or iodides of Al, Ba, Cd, Cu, Fe, Hg, K, Na, Pb, Sr, Zn) -can be measured semiquantitatively despite their relatively slow vaporization from the vaporizer. Even though non-refractory components (e.g., NH 4 NO 3 or (NH 4 ) 2 SO 4 ) vaporize quickly, under certain conditions their differences in vaporization kinetics can result in undesired biases in ion collection efficiency in thresholded measurements. Chemical reactions with oxygen from the aerosol flow can have an influence on the mass spectra for certain components (e.g., organic species). Finally, chemical reactions of the aerosol with the vaporizer surface can result in additional signals in the mass spectra (e.g., WO 2 Cl 2 -related signals from particulate Cl) and in conditioning or contamination of the vaporizer, with potential memory effects influencing the mass spectra of subsequent measurements.Laboratory experiments that investigate these particlevaporizer interactions are presented and are discussed together with field results, showing that measurements of typical continental or urban aerosols are not significantly affected, while measurements of semi-refractory aerosol in the laboratory, close to anthropogenic sources or in marine environments, can be biased by these effects.

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Section: Chemical Reactions With the Vaporizermentioning

confidence: 99%

Section: F Drewnick Et Al: Particle-vaporizer Interactions and Theimentioning

confidence: 99%

Aerosol mass spectrometry: particle–vaporizer interactions and their consequences for the measurements

et al. 2015

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“…In the surface ionization of lithium on pure platinum and on 92% 11,23 platinum-8% tungsten, Datz and Taylor found that the degree of ionization was much smaller than expected and the slope of the Saha-Langmuir line did not agree with the theoretically expected value (as plotted in Fig. 2).…”

Section: -5504mentioning

confidence: 84%

Effect of anionic constituents on the surface ionization of lithium salts

Sloth¹,

Studier²,

Wahlbeck³

1974

J. Phys. Chem.

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“…The surface ionization efficiency for sodium on tungsten has been measured [24]. It increases from 6 to 8 % in the temperature range from 2200 to 2850 K. The extraction efficiency ε extr is higher than the ionization efficiency ε i due to the presence of a penetrating electrostatic field through the exit aperture of the cavity.…”

Section: Ionization and Electrostatic Extractionmentioning

confidence: 97%

Development of a thermal ionizer as ion catcher

Traykov

Dammalapati

et al. 2008

Nuclear Instruments and Methods in Physics Research Section B:

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An effective ion catcher is an important part of a radioactive beam facility that is based on in-flight production. The catcher stops fast radioactive products and emits them as singly charged slow ions. Current ion catchers are based on stopping in He and H 2 gas. However, with increasing intensity of the secondary beam the amount of ion-electron pairs created eventually prevents the electromagnetic extraction of the radioactive ions from the gas cell. In contrast, such limitations are not present in thermal ionizers used with the ISOL production technique. Therefore, at least for alkaline and alkaline earth elements, a thermal ionizer should then be preferred. An important use of the TRIµP facility will be for precision measurements using atom traps. Atom trapping is particularly possible for alkaline and alkaline earth isotopes. The facility can produce up to 10 9 s −1 of various Na isotopes with the inflight method. Therefore, we have built and tested a thermal ionizer. An overview of the operation, design, construction, and commissioning of the thermal ionizer for TRIµP will be presented along with first results for 20 Na and 21 Na.

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Ionization on Platinum and Tungsten Surfaces. I. The Alkali Metals

Cited by 183 publications

References 14 publications

Aerosol mass spectrometry: particle–vaporizer interactions and their consequences for the measurements

Aerosol mass spectrometry: particle–vaporizer interactions and their consequences for the measurements

Effect of anionic constituents on the surface ionization of lithium salts

Development of a thermal ionizer as ion catcher

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