Broadening of the Balmer lines of hydrogen by condensed discharges.---(1) At various pressures, 48 to 250 mm, the intensity distribution was determined for $H\ensuremath{\beta}$, $H\ensuremath{\gamma}$ and $H\ensuremath{\delta}$ by photographing the spectra through a neutral wedge. In each case the broadening was symmetrical, amounting to about 60A for each line at 250 mm, but the curves gave evidences of structure characteristic of each line. The effect of a quenched gap in series with the tube was to increase the broadening, while inductance decreased it. (2) In mixtures with $\mathrm{He}$ or ${N}_{2}$, the broadening was the same as in hydrogen alone at the same total pressure. (3) Stark theory of broadening which relates it to the Stark effect of the electrical fields of the ionized atoms or the radiating atoms, is given mathematical formulation by assuming a probability law for the distribution of the atoms and ions and an inverse square law for the strength of the field, and introducing Sommerfeld's quantum expression for the Stark displacement. This gives $log {I}_{\ensuremath{\lambda}}=log[\frac{a}{({\ensuremath{\lambda}}_{0}\ensuremath{-}\ensuremath{\lambda})}]\ensuremath{-}\frac{b}{({\ensuremath{\lambda}}_{0}\ensuremath{-}\ensuremath{\lambda})}$, where $a=A\ensuremath{\lambda}{\ensuremath{\lambda}}_{0}{p}^{2}f$ and $b=B\ensuremath{\lambda}{\ensuremath{\lambda}}_{0}{p}^{\frac{2}{3}}f$, where $f$ is a known function of the quantum numbers. Comparison with experiment shows agreement as to the general form of the distribution curves. The great broadening produced by the condensed discharge is then due to the momentary high current density and corresponding large proportion of ionized atoms.Neutral wedge cell, filled with an aqueous solution of a black dye, was found more convenient to adjust than the ordinary neutral glass wedge.
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Jan 1, 1931
F Twyman + 2
Open Access