## E/2 mass spectrum

https://doi.org/10.1351/goldbook.M03751
Processes of the charge-@S06054@ type: $\text{M}^{+}+\text{X}\rightarrow \text{M}^{2+}+\text{X}+\text{e}$ occuring in a collision cell (containing a gas, X) located in a field-free region preceding a magnetic and electric sector combination placed in either order, may be detected as follows. If the instrument slits are wide and if the electric sector field $$E$$ is set to half the value required to transmit the main ion-beam, the only ions to be transmitted will be those with a @K03402@/charge ratio half, or almost exactly half, that of the main ion beam. The product ions of the charge-@S06054@ process fulfil this condition. If the magnetic field $$B$$ is scanned, a mass spectrum of such doubly-charged product ions, and thus of their singly-charged precursors, is obtained. Such a spectrum is called an $$\frac{E}{2}$$ mass spectrum. Interference from product ions from processes of the type: $\text{M}_{1}^{+}+\text{X}\rightarrow \text{M}_{2}^{+}+\text{X}+\text{M}_{3}$ where $$m_{1}$$, $$m_{2}$$, and ($$m_{1}- m_{2}$$) are the masses of $$\text{M}_{1}^{+}$$, $$\text{M}_{2}^{+}$$ and $$\text{M}_{3}$$, respectively, and where $$m_{2}=0.5\ m_{1}$$, can arise in $$\frac{E}{2}$$ mass spectra.
Source:
PAC, 1991, 63, 1541. (Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)) on page 1552 [Terms] [Paper]