Retarding potential type energy analyzer

A retarding potential type energy analyzer for measuring an energy of a charged particle emitted from a charged-particle source, using a charged-particle detector, the analyzer comprising:

• a) three grid electrodes sequentially arranged as a front grid electrode, a reference grid electrode and a rear grid electrode in said order between the charged-particle source and the charged-particle detector, in such a manner that a distance between the reference grid electrode and the rear grid electrode is shorter than a distance between the reference grid electrode and the front grid electrode, wherein the reference grid is a single electrode;
• and
• b) a voltage applier for applying voltage to at least one of the three grid electrodes so as to give an upward potential difference with a predetermined magnitude between the reference grid electrode and the front grid electrode as well as a downward potential difference with a magnitude equal to or greater than the upward potential difference between the reference grid electrode and the rear grid electrode, wherein
• a ratio of an absolute value of a potential gradient formed on a side of the rear grid electrode of the reference grid electrode to an absolute value of a potential gradient formed on a side of the front grid electrode of the reference grid electrode is larger than a ratio obtained in a configuration in which a front grid electrode, the reference grid electrode, and the rear grid electrode are equally spaced.