Provided is a compact two-dimensional electron spectrometer that is capable of variably adjusting the deceleration ratio over a wide range, and performing simultaneous measurement of the two-dimensional emission angle distribution with a high energy resolution over a wide solid angle of acquisition. The two-dimensional electron spectrometer is configured from: a variable deceleration ratio spherical aberration correction electrostatic lens; a cylindrical mirror type energy analyzer or a wide angle energy analyzer; and a projection lens. The variable deceleration ratio spherical aberration correction electrostatic lens is configured from: an electrostatic lens that consists of an axially symmetric spherical mesh having a concave shape with respect to a point source, and one or a plurality of axially symmetrical electrodes, and that adjusts the spherical aberration of charged particles generated from the point source; and an axially symmetric deceleration field generating electrode that is placed coaxially with the electrostatic lens.

An electrostatic analyzer includes a cylindrical body having an inner cylinder and an outer cylinder that are coaxial with one another along a longitudinal axis of the cylindrical body. An inner cylindrical electrode is positioned on an exterior face of the inner cylinder. An outer cylindrical electrode is positioned on an interior face of the outer cylinder. A first azimuthal electrode positioned on a face of a first azimuthal plane that passes through the longitudinal axis. A second azimuthal electrode is positioned on a face of a second azimuthal plane that passes through the longitudinal axis. A first end electrode is positioned on a first end face of the cylindrical body. A second end electrode is positioned on a second end face of the cylindrical body.

A charge detection mass spectrometer may include an ion source to generate ions, a mass spectrometer to separate the generated ions as a function of ion mass-to-charge ratio to produce beam of separated ions, an electrostatic linear ion trap (ELIT) including a charge detection cylinder disposed between a pair of coaxially aligned ion mirrors, and means for controlling a trajectory of the beam of separated ions entering the ELIT to cause the ions subsequently trapped in the ELIT to oscillate therein with different planar ion oscillation trajectories angularly offset from one another about the longitudinal axis with each extending along and crossing the longitudinal axis in each of the ion mirrors or with different cylindrical ion oscillation trajectories radially offset from one another about the longitudinal axis to form nested cylindrical trajectories each extending along the longitudinal axis.