Fragmentation Pattern Coefficient
The desorbed gas is ionized by accelerated electrons emitted from the filament of the quadrupole mass spectrometer.
Due to the high energy of the accelerated electrons, some ions undergo fragmentation.
For example, in the case of water (H₂O), the following ions are produced: H₂O⁺, OH⁺, O⁺, H⁺. Here, the simply ionized molecule (H₂O⁺) is called the molecular ion, while the ions (OH⁺, O⁺, H⁺) produced by the cleavage of H₂⁺ are called fragment ions.
The generation ratio between the molecular ion and the fragment ions shows a constant value when ionized under the same conditions.

Fragmentation Pattern Coefficient Table This table shows pattern coefficients for low-molecular-weight compounds frequently observed in temperature-programmed desorption experiments. Pattern coefficients may vary slightly between instruments. Please understand that the values shown here represent average values. Note: These values are for an ionization voltage of 70 eV.

※Fragmentation pattern coefficients may vary slightly depending on ionization energy and mass spectrometer type.