Barclay Physics Wiki

Mass spectrometer[]

The mass spectrometer is an instrument which can measure the masses and relative concentrations of atoms and molecules. It makes use of the basic magnetic force on a moving charged particle or ions. It was invented in 1932 and is comprised of 4 sections the ion chamber, velocity selector, momentum selector and the ion detector.

Mass-spectrometer

Mass spectrometer

Production of ions []

The material which is being weighed first has to be converted into a gas, a process called being volatisied this can be done by rapid heating or using a lazer, the particles are then taken to the mass spectrometer itself. Then the gas has to be ionised having its electrons taken from the particle. The atoms are ionised by being bombarded by high energy electrons which will collide and free electrons from the atoms making them positive ions.

The mass spectrometer will then seperate the differant ions with regards to there size, all the ions have a charge of +1 as there electrons have been liberated from there surfaces. The ions will be attaracted to the negative cathode and will enter the velocity sector where they speed up.

Detection of ions[]

Modern spectrometers use detectors with monitors. These monitor amplify and log the ion current transmitting it into data where it can be put into a mass spectra ready to analyse. The mass spectra shows the distribution of ions according to there masses.