Question

In a common type of mass spectrometer, a beam of ions is passed through a velocity sector with crossed electric and magnetic fields. What is the purpose of the velocity sector?

to strip loose electrons from the ions

to decrease the kinetic energy of the ions

to prevent the ions from traveling in a circular path

to block all ions except those with specific speeds

Answer 1

D). to block all ions except those with specific speeds.

A velocity selector is used with mass spectrometers to select only charged particles with a specific velocity for analysis. It makes use of a geometry where opposing electric and magnetic forces match for a specific particle speed. It therefore lets through undeflected only those particles with the selected velocity