Mass spectrometer question

In the MS to that questions it says dont allow the ions hit the CHARGED plate, why is that? cuz i thought the plat is negative??


Also, in a different question, it says that the charged ions are accelerated by an electric field? but i thought they were accelerated by a negatively charged plate??

Thank you xxx

I would assume it says don’t allow charged because it’s not specific enough. It’s best to say negatively charged plate.

The ions in mass spectrometry are accelerated by an electric field so they all have the same kinetic energy during ion drift stage before they reach the detector.

I hope this helps

Thank you But the MS said just 'plate' and below that said don't allow charged plate

The markscheme says do not allow (transfer of electrons) FROM the charged plate

The markscheme says do not allow (transfer of electrons) FROM the charged plate

wait also I thought the electrons are transferred from the plate to the ions tho, cuz they are positively charged?

wait also I thought the electrons are transferred from the plate to the ions tho, cuz they are positively charged?

Here a quote from the AQA worksheet on mass spec I think might help

“The positive ions hit a negatively charged electric plate. When they hit the detector plate, the positive ions are discharged by gaining electrons from the plate. This generates a movement of electrons and hence an electric current that is measured. The size of the current gives a measure of the number of ions hitting the plate”

I think you're confusing the plate that causes acceleration of the ions (negatively charged) with the detector (not charged)?

Here a quote from the AQA worksheet on mass spec I think might help

“The positive ions hit a negatively charged electric plate. When they hit the detector plate, the positive ions are discharged by gaining electrons from the plate. This generates a movement of electrons and hence an electric current that is measured. The size of the current gives a measure of the number of ions hitting the plate”

ahh I see thank you! But in the quote below, doesn't it suggest that the detector plate and the electric plate are the same? xx sorry to keep disturbing you.

The worksheet separates the different stages - the quote I gave is from the detection stage. So the electric plate is the detector.

Before the quote it talks about the acceleration and it just says the electrons are accelerated by an electric field - this electric field is created by a different electric plate - look at the diagrams.

https://filestore.aqa.org.uk/resources/chemistry/AQA-7404-7405-SG-TOFMS.PDF