3.5 Mass Spectroscopy Flashcards
How are atoms ionised in mass spectroscopy?
Gaseous atoms are bombarded by electrons with sufficient energy to form +1 charge
How does mass spectroscopy work?
Sample vaporised Ionised Accelerated Deflected Detected
How are atoms accelerated in mass spectroscopy?
Charged ions are accelerated by an electric field by repulsion
How are atoms deflected in mass spectroscopy?
Charged particles will be deflected by a magnetic or electric field
Heavier isotopes are deflected less
How are atoms detected in mass spectroscopy?
Electric or photographic methods
How are different isotopes detected in mass spectroscopy?
Radius of path depends on mass charge ratio
Heavier isotopes have larger m/z values so follow a larger radius curve
Most change is due to mass because they have the same charge
Heavier isotopes are deflected less
What would happen if an ion acquires a +2 charge?
It will be deflected more
M/z value is halved
What is a mass spectrum and what does it tell you?
Results of mass spectroscopy
Positions of peaks give atomic masses
Peak intensity gives relative abundance
Abundance adds up to 100%
What is an atomic mass unit?
The mass of a carbon-12 atom divided by 12
What instrument is used to measure the mass of atoms?
Mass spectrometer
What does the velocity sector do in a mass spectrometer and why is it important?
Makes sure atoms are travelling at the same speed so in the next section it will only be affected by mass or charge
What does the amount atoms are deflected by depend on in mass spectroscopy?
Mass and charge on ion
Why is the strength of the magnetic field steadily increased in mass spectrometry?
To allow other ions to pass through as only one particular mass charge ratio will pass through and be detected
What does the detector ultimately show in mass spectrometry?
The ratio of ions that pass through at each setting and each setting of the velocity flashcards
What do the peaks in a mass spectrum tell you?
The relative abundance
