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    Experimental Procedure for RGA Mass Spectrometer

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    Experimental Procedure for RGA Mass Spectrometer.
    Ionizer Setup
    Ionization Energy: 35V
    Electron Emission: 0.5mA
    Ion Energy: Low 8eV
    Focus Plate Voltage: 45
    Scan/Log Setup
    Initial [Mass] : 120[amu]
    Steps [steps/amu]: 25
    Final [Mass] ; 145[amu]
    Disable After: 1[scan]

    Xenon is a monatomic element. Therefore, no fragmentation occurs and the peaks in the mass spectrum are solely attributable to xenon ions.

    1. Write all m/z values you obtained.

    2. Write all Xe isotopes you detected using standard notaion

    3. Determine the natural abundances
    ( the height of a peak in the mass spectrum is directly proportional to the number of ions with that mass-to-charge ratio. The total number of ions detected corresponds to the sum of the ion counts for all peaks in the mass spectrum attributable to analyte ions. Find the percent abundance of each Xe isotope)

    4. Determine the average atomic mass
    (the mass spectrometric data allows you to calculate the average atomic mass of xenon. Obtaining the average atomic mass requires a weighted average wherein the atomic mass of each isotope must be weighted (multiplied) by the % abundance of each isotope)

    5. Compare the types and abundances of Xe isotopes you found with those reported in the literature. Were you able to detect all Xe isotopes reported in the literature? If not, what do you think is the reason?

    6. Compare the average atomic mass of Xe you obtained with the literature value. What is the % eror of your measurement?
    (% error= the difference b/w two values/ reported average atomic mass of Xe)

    7. Explain why were there few if any +2 species detected in your experiment.

    8. The most abundant mass number for the +1 xenon dimer ion is 261. Identify all isotopomers that contribute to the signal at this mass value. Estimate what fraction of the total dimer signal appears at mass 261. (detection of Xe2+ would require a more sophisticated apparatus.)

    9. Sketch the σ(5pz) and σ*(5pz) molecular orbitals of Xe2. Does it matter which of the two orbitals loses an electron if one wants to form a stable +1 cation? Explain.

    10. Creating a histogram of the data.

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    Solution Summary

    The solution discusses the experimental procedure for RGA mass spectrometer.