| abstract |
A mass spectrometer includes an ion source for producing a primary ion beam, which has a heatable ion emitter coated by a liquid metal layer essentially comprised of pure metallic bismuth or of a low-melting-point alloy containing, in essence, bismuth. A bismuth ion mixed beam can be emitted by the ion emitter under the influence of an electric field. From said bismuth ion mixed beam, one of a number of bismuth ion types whose mass is a multiple of monatomic singly or multiply charged bismuth ions Bi 1 p+ , is to be filtered out in the form of a mass-pure ion beam that is solely comprised of ions of a type Bi n p+ , in which n≧2 and p≧1, and n and p are each a natural number. |