COSAM » Departments » Chemistry & Biochemistry » Facilities » massspec » Learn about mass spectrometry » MALDI-TOF » Time of Flight

A time-of-flight mass spectrometer contains a tube that the ions travel through.  In linear mode, the entrance is where the ions are created and the other end contains the detector.  A couple of equations relate the time the ion is in the tube to the mass of the ion.

Kinetic Energy (KE) = 1/2*mass*velocity2

KE = 1/2mv2

or

velocity_relation_to_kinetic_energy.png

Then the time in the flight tube is related to the length (or distance) of the flight tube.

time_equals_distance_divided_by_velocity.png

Substitute velocity (v) to get

time_equals_distance_divided_by_the_square_root_of_two_times_the_kinetic_energy_divided_by_the_mass.png

Simplify and we see that the flight time is proportional to the square root of the mass of the ions.  Notice the ion kinetic energy is also important.  We will discuss this more in the reflectron section.

time_is_proportional_to_mass.png



Last Updated: 05/17/2019