Ammonia maser 2026-10-18
An ammonia maser uses an ammonia molecular beam, maser state selection and a maser cavity to obtain amplification or sustained microwave oscillation. In the 1954 experiment by James Power Gordon, Herbert Jack Zeiger and Charles Hard Townes, a quadrupolar static electric field focused upper-state molecules toward the cavity and deflected lower-state molecules away. The reported ammonia inversion transition lies near .[ref]
Figure 1. . Upper states enter the maser cavity; lower states are rejected. Paths and spacing are illustrative. The inset shows the selector end view.[ref] Details.
Maser history 2026-10-18
The 1955 paper by James Power Gordon, Herbert Jack Zeiger and Charles Hard Townes acknowledged Nikolay Basov and Aleksandr Prokhorov's independent proposal.[ref] The latter authors' theory paper states that they presented the molecular-generator possibility in May 1952, cites their 1954 publication, and separately cites the Gordon–Zeiger–Townes experimental realization. These are contributions from independent groups.[ref]