Field Ionisation Studies Using a Double Focussing Mass Spectrometer

1966 ◽  
Vol 21 (6) ◽  
pp. 776-779 ◽  
Author(s):  
J. H. Beynon ◽  
A. E. Fontaine ◽  
B. E. Job
Keyword(s):  
Mass Spectrometer ◽  
Single Molecule ◽  
Mass Spectra ◽  
Ion Source ◽  
Energy Spread ◽  
Small Energy ◽  
Intense Field ◽  
Ionisation Mass

Intense field ionisation mass spectra have been obtained with an A.E.I. M.S.7 mass spectrometer, used with very simple modifications to the ion source.Some features of the spectra of a variety of compounds are given and the spectrum of acetone is discussed in detail. A special feature of this spectrum is the variety of ions with a mass greater than that of a single molecule.The relatively small energy spread of the field ion source enabled resolving powers, higher than those possible with a spark source, to be obtained. Multiplets occurring in the spectra were easily resolved.

scholarly journals Measurements of hydroperoxy radicals (HO<sub>2</sub>) at atmospheric concentrations using bromide chemical ionisation mass spectrometry

2019 ◽  
Vol 12 (2) ◽  
pp. 891-902 ◽  
Author(s):  
Sascha R. Albrecht ◽  
Anna Novelli ◽  
Andreas Hofzumahaus ◽  
Sungah Kang ◽  
Yare Baker ◽  
...  
Keyword(s):  
Water Vapour ◽  
Mass Spectrometer ◽  
Ion Source ◽  
Detection Sensitivity ◽  
Detection Methods ◽  
Integration Time ◽  
Key Species ◽  
Atmospheric Concentrations ◽  
Chemical Ionisation ◽  
Ionisation Mass

Abstract. Hydroxyl and hydroperoxy radicals are key species for the understanding of atmospheric oxidation processes. Their measurement is challenging due to their high reactivity; therefore, very sensitive detection methods are needed. Within this study, the measurement of hydroperoxy radicals (HO2) using chemical ionisation combined with a high-resolution time-of-flight mass spectrometer (Aerodyne Research Inc.) employing bromide as the primary ion is presented. The sensitivity reached is equal to 0.005×108 HO2 cm−3 for 106 cps of bromide and 60 s of integration time, which is below typical HO2 concentrations found in the atmosphere. The detection sensitivity of the instrument is affected by the presence of water vapour. Therefore, a water-vapour-dependent calibration factor that decreases approximately by a factor of 2 if the water vapour mixing ratio increases from 0.1 % to 1.0 % needs to be applied. An instrumental background, most likely generated by the ion source that is equivalent to a HO2 concentration of (1.5±0.2)×108 molecules cm−3, is subtracted to derive atmospheric HO2 concentrations. This background can be determined by overflowing the inlet with zero air. Several experiments were performed in the atmospheric simulation chamber SAPHIR at the Forschungszentrum Jülich to test the instrument performance in comparison to the well-established laser-induced fluorescence (LIF) technique for measurements of HO2. A highly linear correlation coefficient of R2=0.87 is achieved. The slope of the linear regression of 1.07 demonstrates the good absolute agreement of both measurements. Chemical conditions during experiments allowed for testing the instrument's behaviour in the presence of atmospheric concentrations of H2O, NOx, and O3. No significant interferences from these species were observed. All of these facts demonstrate a reliable measurement of HO2 by the chemical ionisation mass spectrometer presented.

Photochemical Studies by Means of a Field Ion Mass Spectrometer

1966 ◽  
Vol 21 (1-2) ◽  
pp. 135-140 ◽  
Author(s):  
H. Okabe ◽  
H. D. Beckey ◽  
W. Groth
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Flow System ◽  
Low Pressure ◽  
Ion Source ◽  
Mass Spectrometric ◽  
Gas Pressure ◽  
Spectrometric Investigation ◽  
Mercury Lamp ◽  
Mass Spectrometric Investigation

A mass spectrometric investigation was carried out on the direct photolyses of propene, 1-butene, and hydrazine at 1849 A with a field ion source in a flow system. Comparisons were made with Pt tip and wire emitters. It was found that, without illumination, mass spectra obtained with the wire were accompanied by a number of fragment peaks amounting to almost 1%. Since these peaks interfere with those produced photochemically, the tip emitter was used mostly for the photochemical studies although it gave 100 times less current and was less stable. The photochemical products formed at a gas pressure of 10 μ by a low pressure mercury lamp were detected after approximately 10 m sec. The three main peaks observed in the propene photolysis were at masses 27, 28, and 56, indicating the processes:C3H6+hv→C2H3+CH3, C3H6+hv→C2H4+CH2, CH2+C3H6→C4H8.The photolysis of 1-butene gave four main peaks at masses 40, 41, 42, and 70, suggesting steps, C4H8+hv→C3H4+ (H+CH3) or CH4, C4H8+hv→C3H5+CH3, C4H8+hv→C3H6+CH2, CH2+C4H8C5H10.The only peak found with the photolysis of hydrazine was at mass 17, indicating the step, N2H4+hv→NH3+NH.The possibility of forming these products by secondary processes is discussed.

Improved TIMS data reliability and precision with new ion source design

2019 ◽  
Vol 34 (5) ◽  
pp. 986-997 ◽  
Author(s):  
Herbert Siegmund ◽  
Joe Hiess ◽  
Monika Sturm ◽  
Andreas Koepf ◽  
Christian L'Herault ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
High Voltage ◽  
Ion Source ◽  
Data Reliability ◽  
Ionisation Mass ◽  
Ionisation Mass Spectrometer

The ion source design of the Triton and Triton Plus Thermal Ionisation Mass Spectrometer (TIMS) has been improved to reduce the frequency and intensity of high voltage electric sparking.

scholarly journals Interaction of Fullerenes with Organosilanes in the Ionization Chamber of a Mass Spectrometer under Electron Impact and the Reaction of C60with Tetraphenylsilane in Solution under UV Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Yury I. Lyakhovetsky ◽  
Elena A. Shilova ◽  
Alexandra P. Pleshkova ◽  
Alexander I. Belokon ◽  
Sergey O. Yakushin ◽  
...  
Keyword(s):  
Electron Impact ◽  
Mass Spectrometer ◽  
Uv Irradiation ◽  
Ionization Chamber ◽  
Ion Source ◽  
Organic Radicals ◽  
Mechanistic Study ◽  
Mass Spectral ◽  
Additional Support ◽  
Derivatives Of

C60was shown to react with organosilanes Me4Si, Ph2SiH2, Ph2MeSiH, Ph4Si, andα-naphthylphenylmethylsilane in the electron ionization ion source of a mass spectrometer with the transfer of the corresponding organic radicals (Me, Ph, andα-naphthyl) from the silanes to the fullerene. The reactions were accompanied by hydrogen addition to some products and hydrogen loss from them. C70reacted with Me4Si analogously. A reaction mechanism involving homolytic dissociation of the silanes under electron impact to the corresponding organic radicals, which react further with C60at the surface of the ionization chamber of the mass spectrometer to give the respective adducts, was offered. A mechanistic study of the reaction of C60with Me4Si supported it. No silicon containing derivatives of the fullerenes were found. C60reacted with Ph4Si in solution under UV irradiation in a similar fashion furnishing phenyl derivatives of the fullerene. These results provide an additional support to the hypothesis formulated earlier thatthe homolytic reactive mass spectrometry of fullerenes (the reactions of fullerenes with other species in the ionization chambers of mass spectrometers and their mass spectral monitoring)can predict the reactivity of them toward the same reagents in solution to a significant extent.

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