Gas excitations using high frequency deflected electron beams: A convenient method for determinations of atomic and molecular lifetimes

As pointed out earlier, gas jets excited with a monoenergetic electron beam in the keV, mA region yield intense atomic and molecular spectra. It has also been shown that high-frequency sweeping of the electron beam and fast-coincidence techniques convert this light source to a convenient method for determining atomic and molecular lifetimes. An improved version of such an apparatus has now been completed, being designed for 2-20 keV, 300 mA electrons and a variable sweep frequency. The apparatus has just been tested on a great number of lifetimes in the range 1-10 000 ns in atoms and molecules such as H, He, N, O, C ₂, CH, CH ⁺, CO ₂⁺, N ₂, N ₂⁺, and O ₂⁺. Good agreement is obtained in most cases where measurements using other techniques are available. Presumably this high frequency deflection technique will find its most important applications in determining lifetimes in molecules of vital astrophysical interest including transitions in the infrared region.