Analysis of charged particles for charge, mass and energy

Analysis of charged particles for charge, mass and energy 

As a rule, charged-particle analysers use the difference in mass-to-charge ratio mJe of electrons or ionized atoms or molecules to separate them from each other. In this context, mass spectrometry is a versatile method for distinguishing individual species (atoms or molecules), and also for determining chemical and structural information about molecules. Molecules have distinctive fragmentation patterns that provide structural information and also reveal information about intra-molecular mechanisms of coupling between potential energy surfaces. 

All commonly used charged-particle analysers use electric and magnetic fields to apply a force on charged particles (electrons, and positive and negative ions). The relationship between force, mass, and the apphed fields is described by using two basic equations, namely Newton s second law and the Lorentz force law  

From Equations (13.1a) and (13.1b), it is evident that the force causes an acceleration that is mass dependent (Newton s second law), and that the applied force is linked to the charge of the particle (Lorentz s force law). Consequently, charged-particle analysers (specifically mass spectrometers) separate the particles according to their mass-to-charge ratio (m/z) rather than by their mass alone. Analysers need to be able to (i) separate the ions in space or time, based on their mass-to-charge ratio, and (ii) quantify how many particles of a specific mass-to-charge ratio reached a charge-sensitive detector. 

A scanning charged-particle analyser can be viewed as being analogous to the equipment used in optical spectroscopy for analysing the wavelength components of received light. Recall that 

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