Qz-value

To be fire resistant, a material should have a low Qz value and a low A value another possibility is that the material contains elements which, on decomposition, form combustion inhibitors (Cl- and Br-containing polymers). Qz will be low if only small amounts of combustible gases develop in the pyrolysis, for instance, because the material chars considerably and mainly splits off carbon dioxide and water. The residue of pyrolysis or the sum of the residue and the weight of carbon dioxide and water formed by pyrolysis may be used as a rough measure of non-flammability. 

Principle of resonant ejection. Upper ions are stored in the 3D trap at a voltage Va of the fundamental RF. An additional RF is applied to the end caps corresponding to qz = 0.8. On increasing V (lower panel) ions are moved to higher qz values. In the figure, the smallest ion has reached qz = 0.8 and is ejected by resonance. This ejection occurs at a lower value of V than the one needed to eject by instability at qz = 0.908. 

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