Molecular ion

An ion formed simply by the removal from (positive ions) or addition to (negative ions) a molecule of one or more electrons. For molecules containing multi-isotope elements, a number of different isotopologue molecular ions will be formed. The ion containing the most abundant naturally occurring isotopes of all atoms that make up the molecule is called the monoisotopic molecular ion, and the mass of the molecular ion is, by definition, calculated for this ion using therefore the masses of the most abundant isotopes with a correction for the masses of the electron(s) that were added or removed. For instance, electron ionization of BF₃ gives two isotopologue ions, ¹⁰B¹⁹F₃^+. of m/z 67 and ¹¹B¹⁹F₃^+. of m/z 68, the heavier one being the monoisotopic molecular ion since ¹¹B is more abundant than ¹⁰B. ¹⁰B¹⁹F₃^+. is termed an isotopic molecular ion.

Related Terms

Isotopologue Ion Isotopic Molecular Ion Base Isotope Cluster Ion