Analyser arrangement for particle spectrometer

A photo-electron spectrometer of hemispherical deflector type for analysing a particle emitting sample by determining at least one parameter related to charged particles emitted from the particle emitting sample, the spectrometer comprising:

• a measurement region having an entrance allowing said particles to enter the measurement region, the entrance being a slit;
• a lens system for forming a particle beam of said charged particles and transporting the particles between said particle emitting sample and said entrance of the measurement region, said lens system operated in angular mode and having a substantially straight optical axis;
• a deflector arrangement comprising a first deflector for deflecting the particle beam in at least a first coordinate direction perpendicular to the optical axis of the lens system before entrance of the particle beam into the measurement region;
• a detector arrangement for detecting the positions of the charged particles in the measurement region, said positions being indicative of said at least one parameter;
• and
• a control unit operable to cause the deflector arrangement to deflect the particle beam such that a predetermined part of the angular distribution of the particles forming the particle beam passes the entrance of the measurement region;
• wherein said detector arrangement is configured to determine the positions of the charged particles in two dimensions, one of which is used to detect the energies of the particles and one of which is used to detect the start directions of the particles in the direction along the slit, and
• wherein said deflector arrangement further comprises at least a second deflector operable for deflecting the particle beam in the same at least first coordinate direction at least a second time before entrance of the particle beam into the measurement region to detect the start directions of the particles in the direction across the slit so that the detection of the start directions is performed in a two-dimensional manner with respect to a plane of the slit.