Controlling the resolution of static mass spectrometers using intermediate slit diaphragms
T15N4
A.S. Antonov, A.S. Berdnikov, L.N. Gall, V.D. Sachenko
The paper shows how to increase effectively the resolving power and transmission of a static mass spectrometer (implying here an optimal compromise between these parameters) using the optimally positioned intermediate slit diaphragms in order to ensure a minimum loss of the sensitivity of a device.
Transmission for quadrupole mass filter with dipolar excitation
T15N2
K.E. Seregin , N.V. Konenkov , A.S. Berdnikov
Using the numerical simulation of the ion trajectories in the linear quadrupole with the dipole excitation(s) the mass peaks are calculated. Using this data the diagrams for transmission versus resolution are calculated both for the ideal quadrupole field and for the quadrupole field with round rods. It is shown that using the dipole excitation mode the resolution may be increased from R0.1 = 1000 to R0.1 = 2200 with 20% QMF transmission in ideal case, and for the round rods the dipole excitation along iso-line βy = 0.01 enables to increase the resolution R0.1 from 500 to 800 at 20% level transmission.
A new approach to increase the resolution of the mass spectrometer with wedge-shaped reflectors
T13N4
E.A. Sysoeva, A.V. Spakhov, Alexander A. Sysoev
The paper describes the investigation of ion-optical properties of a laser TOF mass spectrometer including two successively positioned wedge-shaped ion mirrors. Some specific properties of the configuration of ion trajectories near their reflection in the second ion reflector have been found. The dependence of aberrations on the ion energy was acquired the toothed shape for the resolution of the analyzer higher than 3000-5000. An approximation of the dependence gave a polynom of the 15-th degree. The calculation of polynomial coefficients showed a great contribution into the duration of ion packets for aberrations of higher order. The discovered features allowed us to suggest a way of local correction of nearby trajectories in the full flow of ions. By correcting the local motion of individual groups of ions it was possible to reduce temporary aberration up to 1−1.6 ns depending on the ion energy. For the time of ion flight ~ 35 μs, such duration limits the resolution of the analyzer by a value not less than 10000. The real length of the ion drift path was about 30 cm. The total overall sizes of the ion-optical system were ~ 24 cm × 19 cm × 5 cm.
