The disclosure features methods and systems that include directing an ion beam to a region of a sample to liberate charged particles from the region of the sample, where the directed ion beam is pulsed at a first repetition rate, deflecting a first subset of the liberated charged particles from a first path to a second path different from the first path in response to a gate signal synchronized with the repetition rate of the pulsed ion beam, and detecting the first subset of the liberated charged particles in a time-of-flight (TOF) mass spectrometer to determine information about the sample, where the gate signal sets a common reference time for the TOF mass spectrometer for the first subset of charged particles liberated by each pulse of the ion beam.

The disclosed techniques relate to a residual gas analyzer, in particular for analyzing a residual gas in an EUB projection exposure apparatus, including a mass spectrometer and an admission device for admitting ionized constituents of the residual gas from a vacuum environment into the mass spectrometer. The admission device includes an ion decelerator, with the ion decelerator having an adjustable deceleration voltage in order to subject the ionized constituents to selection with respect to kinetic energy before being transferred into the mass spectrometer. The disclosed techniques also relate to a projection exposure apparatus including such a residual gas analyzer, and a method for residual gas analysis.

Improved multi-pass time-of-flight mass spectrometers MPTOF, either multi-reflecting (MR) or multi-turn (MT) TOF are proposed with elongated pulsed converterseither orthogonal accelerator or radially ejecting ion trap. The converter 35 is displaced from the MPTOF s-surface of isochronous ion motion in the orthogonal Y-direction. Long ion packets 38 are pulsed deflected in the transverse Y-direction and brought onto said isochronous trajectory s-surface, this way bypassing said converter. Ion packets are isochronously focused in the drift Z-direction within or immediately after the accelerator, either by isochronous trans-axial lens/wedge 68 or Fresnel lens. The accelerator is improved by the ion beam confinement within an RF quadrupolar field or within spatially alternated DC quadrupolar field. The accelerator improves the duty cycle and/or space charge capacity of MPTOF by an order of magnitude.

Systems and methods are disclosed for dynamically switching an ion guide and a TOF mass analyzer between concentrating or not concentrating ions in a targeted acquisition. Product ions are ejected from the ion guide into the TOF mass analyzer and the intensity of a known product ion is measured at two or more time steps. The ion guide initially ejects product ions using a sequential or Zeno pulsing mode that concentrates product ions with different m/z values within the TOF mass analyzer at the same time. If the intensity of the product ion is increasing and greater than a threshold intensity, the ion guide switches to a continuous or normal pulsing mode that does not concentrate ions with different m/z values in the TOF mass analyzer at the same time. Similarly, if the intensity decreases below a threshold in continuous mode, the ion guide switches back to sequential mode.

Improved multi-pass time-of-flight mass spectrometers MPTOF, either multi-reflecting (MR) or multi-turn (MT) TOF are proposed with elongated pulsed converterseither orthogonal accelerator or radially ejecting ion trap. The converter 35 is displaced from the MPTOF s-surface of isochronous ion motion in the orthogonal Y-direction. Long ion packets 38 are pulsed deflected in the transverse Y-direction and brought onto said isochronous trajectory s-surface, this way bypassing said converter. Ion packets are isochronously focused in the drift Z-direction within or immediately after the accelerator, either by isochronous trans-axial lens/wedge 68 or Fresnel lens. The accelerator is improved by the ion beam confinement within an RF quadrupolar field or within spatially alternated DC quadrupolar field. The accelerator improves the duty cycle and/or space charge capacity of MPTOF by an order of magnitude.

An ion optical component includes at least one electrode assembly including a circular segment-shaped inner electrode and a ring segment-shaped outer electrode surrounding the inner electrode along a circumference, and two circular segment-shaped plates surrounded on both sides by the inner electrode and circumferentially surrounded by the outer electrode and including a uniform ring-shaped gap between each of the plates and the outer electrode. The ion optical component includes two electrode assemblies, each of which extends over a sector with an angle of about /2, where 90<<180, and are positioned one behind the other in such a way that a trajectory of an ion beam through the ion optical component is S-shaped and focused in two spatial directions.