A new-regime Wiley–McLaren time-of-flight mass spectrometer

A modified version of the classic Wiley–McLaren time-of-flight mass spectrometer (TOFMS) is presented here. Owing to a second-order compensation of the initial position effect, a mass resolution m/δm higher than 2000 is obtained with large ion volumes, of the order of 0.2 cm3 for Na+55 (1265 a.m.u.). Sodium clusters Na+n with n up to 530 (≂12200 a.m.u.) are separated. The spectrometer can be used for the analysis of ionized clusters in a mass range from 1 to about 20000 a.m.u. as well as for the measurement of the kinetic energy of molecular fragments after a Coulomb explosion of a molecule. The performance of this spectrometer is demonstrated with sodium clusters and molecules.