Investigation of the fine structure in the²D sequence of sodium using level-crossing spectroscopy

Abstract

Abstract. The fine-structure splittings in the n2D sequence of sodium were measured for n = 4-9. An accuracy of about 0.1% was obtained in level-crossing measurements on an atomic beam. The D states were populated by step-wise excitation, using an RF lamp and a cw dye laser. A method for measuring the sign of the spin-orbit coupling constant is demonstrated. With the present measurements, the highly anomalous nZD sequence in sodium has now been studied for n = 3-16.

Atomic spectroscopy by resonance scattering

“…By combining laser excitation with optical resonance methods such as radiofrequency resonance and level-crossing spectroscopy, the demands on laser linewidth and stability can be greatly reduced although a maximal resolution is retained. By using stepwise excitations, as illustrated in figure 1, studies of hyperfine and fine structures, as well as Stark effect studies for a large number of normally optically inaccessible alkali states, could be performed (Svanberg et al I973;Fredriksson & Svanberg 1976;Svanberg I977 experiments, polarized light is used to create unequal populations on the different substates of the excited atom. As a consequence of this the fluorescence light will be polarized and the polarization is partly retained in the cascade decay.…”

Precision determination of the fine-structure splittings of the 5d and 6d states in potassium

“…A more accurate value for gl is 1-m~=0.999986 (ml=electron mass, % m n --nuclear mass). The expressions for the second and third crossings are somewhat more complicated [9]. Using such expressions the evaluation of the finestructure intervals is straight-forward.…”

“…In the present work we have made a precision determination of the fine-structure splittings of the 5 and 6 2D states using level-crossing spectroscopy. The experimental technique, previously used in this laboratory for fine-structure studies in sodium [8,9] and lithium [10], yields a spectroscopic resolution only limited by the Heisenberg uncertainty relation and not by Doppler broadening or laser frequency jitter. The fine-structure interval is determined from measured level-crossing positions, essentially employing the Breit-Rabi formula for the fine structure [11].…”

“…A large iron-magnet system had to be used to produce the necessary field strengths. In our corresponding experiments on sodium [9], Helmholz coils could be used. A powerful rf discharge lamp could be employed for the first excitation step, whereas a CW dye laser was used for the second one.…”

Hyperfine structure in the sequence of sodium S states

“…For example, the anomalous fine-structure in the sequence of D states has been extensively investigated in two-photon absorption, quantum-beat, and level-crossing experiments (Salour 1976, Fabre et al 1975. Fredriksson and Svanberg 1976.…”