| 摘要 |
Apparatus and a related method for detecting signal photons of a selected wavelength using ionization induced by collisions between atomic or molecular particles. Signal photons raise the energy level of a proportion of particles introduced into a detection chamber to a selected metastable state. Optionally, a pump laser assists in raising the energy level of the particles to a metastable state close to the ionization continuum. Collisions between particles in the selected metastable state and particles of the buffer gas cause ionization of the metastable particles, and a measurable electrical current is obtained, without the need for strong electric fields for ionization, or the need for strong optical fields for photoionization. In a variant form of the invention, a second substance is admitted into the detection chamber. Collisions between the original atomic or molecular particles and particles of the second substance cause ionization of the second substance, again providing a measurable electric current from the free electrons or ions that are produced.
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