6533b7d3fe1ef96bd1260a70

RESEARCH PRODUCT

Collinear fast-beam laser spectroscopy

subject

description

The progress in atomic and molecular spectroscopy has gone hand in hand with improvements of the resolution. Before the tunable narrow-band lasers led to the invention of Doppler-free techniques, spectral lines from cooled hollow-cathode discharges(1) had typical widths larger than 300 MHz, and high resolution was achieved only in rf spectroscopy, e.g., within hyperfine structure multiplets, by the classical techniques like atomic beam magnetic resonance,(2) optical pumρing,(3) or double resonance.(4) While the Doppler broadening $$\delta {v_D} = {v_0}{\left( {{{8kT{\rm{ }}\ln {\rm{ 2}}} \over {m{c^2}}}} \right)^{1/2}}$$ (1) is negligible for resonance frequencies v 0 in the rf regime, the narrowing of optical resonances by cooling to low temperatures, T, has obvious limits. On the other hand, Eq. (1) holds for an isotropic thermal velocity distribution, and a narrow Doppler width requires a reduction in the spread of velocity components only along the direction of observation. It is well known from ion optics that this can be achieved by electrostatic acceleration.