摘要:
A method of selecting a material for the construction of a multipole mass filter that is temperature stable or in other words, the R.sub.o parameter remains invariant with change in temperature. The coefficients of thermal expansion of the quadrupole rods and mounting structure are chosen so that a constant ratio of the two is provided which in turn is determined by the geometrical construction of the filter.
摘要:
Apparatus and method for programming the ion energy of ions being analyzed by a quadruple mass spectrometer where the axis potential applied to the quadruple rods is caused to vary in synchronism with a mass scan in order that the ions of each mass being analyzed may transit the quadruple with the most advantageous energy for proper analysis (that is, with substantially equal velocities) and the application of the ion scan voltage will not distort the fringing field at the entrance to the quadrupole.
摘要:
In a mass spectrometer a focusing ion lens system effectively separates charged from neutral particles by forming a potential well along the axis from the ionizing region to the mass analyzer by the use of a gridded lens system. The grids by the use of a high-low voltage combination form the potential well while at the same time allowing nonselected neutral particles to pass through the grid. Thus, the system is very effective for relatively high pressure ionizing regions where a large amount of neutral particles are generated.
摘要:
In a vacuum system a baffle-valve acts first as a baffle to reduce the backstreaming of a diffusion pump fluid into the main vacuum chamber being evacuated and secondly it can be used as a valve to provide complete isolation between the diffusion pump and the vacuum chamber. This enables the chamber to be open for service work while the diffusion pump is kept operating for rapid pump down. The foregoing dual use of the baffle/valve increases pumping efficiency because of higher conductance.
摘要:
An unbalanced radio frequency voltage is supplied between two pairs of conductive rods of a quadrupole mass filter of a mass spectrometer system. Means are provided for d.c. voltage polarity reversal for monitoring positive and negative ions. The d.c. voltage is derived by rectification of the radio frequency voltage.
摘要:
There is described a method of operating an ion trap mass spectrometer. The method is carried out by trapping ions of selected masses in a three-dimensional field and then generating at least two fields in said trap having different frequencies to excite multiple trapped ions.
摘要:
This invention relates generally to a quadrupole ion trap mass spectrometer and method of operation and more particularly to an ion trap mass spectrometer in which pulses of energy of predetermined frequencies are applied across the end caps to independently and sequentially excite ions of different masses trapped in the ion trap to perform parent scanning, neutral loss scanning and selected reaction monitoring.
摘要:
Disclosed is quadrupole ion trap mass spectrometer of the type including a ring electrode and end caps defining a trap volume and including means for introducing sample ion into the ion trap and means for applying voltages to the electrodes. Further included are means for applying two resonant excitation waveforms at two different frequencies and two different voltages between the end cap electrodes to simultaneously excite multiple ions in the ion trap volume.
摘要:
In a hybrid mass spectrometer, a high-energy collision chamber (8) is arranged in a field-free region (12) which, in the direction of travel of the ions, is located after the first stage (1 to 6). A lens arrangement (9) serves for decelerating daughter ions of different energies to a fixed energy, and preferably at the same time also for shaping the ion beam. Preferably, the hybrid mass spectrometer is of BEQQ configuration.