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    In TOF mass spectrometry, I've consulted different sources and am unsure on whether ionisation part is caused by 'an electron gun' or whether it 'passes through needle and then evaporates to form positively charged droplets/ions'

    I've been taught its the second one however when I look at the mark scheme they use the first explanation, can someone just clarify/clear this up for me please. Thank you so much.

    It's better to use the second one in the exam but sometimes they accept the first.
    The electron gun is the needle which the specimen passes through i believe

    Hi DCC1999

    The older specifications used to ask about mass spectrometers which relied on electromagnetism and deflection rather than time of flight. The first kind was described in terms of the electron gun whereas the latter talks about the high voltage needle. The mark schemes you are looking at and practicing from are for old exam questions which is where the confusion occurs.

    You can check out this page for help with TOF mass spec if needed.


    Hope that helps

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