Possibility of operating quadrupole mass filter at high resolution

Quadrupole mass filter acceptance in stability island created by double-frequency quadrupole excitation

“…It is explained by one-dimensional ions filtration character in the X-band mode (along the x direction only) that significantly influences QMF acceptance (the volume of the phase space of initial conditions for ions transmitted by filter). In the X-band mode, filter acceptance along y is much higher than that along X S y ) S x À Á , while in the normal mode, they are similar according to the theory developed by Sudakov et al 8 It is claimed 5,7 that resulting acceptance is equal to the product of acceptances along the axes: V ¼ S x S y ; therefore, in the normal mode, V is proportional to the second power of a small parameter r 0 f 2 (r 0 is the field radius, i.e. radius of the inner circle touching the electrodes), and in the X-band mode, it is proportional to the first power only that indicates the better QMF transmission in the X-band mode compared to the normal mode.…”

“…For QMF, ''X-band'' is of interest because the scan line crosses it at a larger angle, and the amplitude of unstable ions increases faster that allows to reduce the sorting time. 5,7 QMF transmission coefficient is claimed 5,7 to be higher in the X-band than in the normal mode at the same resolution. It is explained by one-dimensional ions filtration character in the X-band mode (along the x direction only) that significantly influences QMF acceptance (the volume of the phase space of initial conditions for ions transmitted by filter).…”

“…Mass peak tails can be significantly damped and the time required for ion sorting can be reduced when operating close to the upper stability island top. 4 Quadrupole excitation by two harmonic signals having different frequencies (in addition to RF field) was proposed by Sudakov et al [5][6][7] For certain values of excitation amplitudes and frequencies, a long and narrow stability band emerges instead of stability islands.…”

Stable X-islands of quadrupole mass filter

“…Sudakov et al 10,11 proposed the quadrupole excitation by two auxiliary harmonic signals with different frequencies. In this case, a narrow single stability X-band is formed on the stability diagram.…”

Quadrupole mass filter operation with dipole direct current and quadrupole radiofrequency excitation

“…Sudakov and co‐workers proposed quadrupole excitation by two auxiliary harmonic signals having different frequencies (in addition to the main rf field). For certain amplitudes and rf frequencies, a narrow stability X‐band is formed in the stability diagram.…”