Studies of Hyperfine Structure of LaI by Laser Spectroscopy on Atomic Beam

Abstract

High-resolution Doppler-reduced laser spectroscopic investigations on an atomic beam of 139 La were carried out to study hyperfine structure of 8 odd levels. The magnetic-dipole coupling constants A and the electric-quadrupole coupling constants B were determined and compared with the data from literature, if available.PACS numbers: 35.10.Fk IntroductionThe first works concerning the electronic (fine and hyperfine) strncture of lanthanum atom were conducted already in the twenties and thirties of this century.Meggers [1] in 1932 performed first measurements of a large number of spectral lines of lanthanum atom; on the basis of those measurements Russell and Meggers [2] carried out identification of many electronic levels, mostly belonging to the low-lying configurations; this identification has in most cases been confirmed in later works.The first theoretical works, concerning the even configurations, were conducted by Stein [3]. The assignment of the theoretically determined electronic levels to the measured ones, for the even configurations, was performed by Wilson [4] and Ben Ahmed et al. [5,6], who used the least squares method.Anderson [7] was in 1934 the first to investigate the hyperfine stucture of the isotope 139 of lanthanum atom, using a combination of a spectrograph and a Fabry-Perot interferometer. The continuation of those measurements were the works of Murakawa and Kamei [8], Luhrs [9] and Fischer et al. [10], while Ben Ahmed [11] used Fourier spectroscopy. All of those investigations, performed by means of the classical optical spectroscopy, were of a rather limited accuracy.The first precise measurements of the hyperfine structure of the levels belonging to the ground term were performed by Ting in 1957 [12] with the use of the atomic beam magnetic resonance (ABMR) method. The magnetic-dipole (A), electric-quadupole (B) and magnetic-octupole (C) hyperfine splitting constants were obtained.

Experimental investigations of the hyperfine structure in neutral La: I. Odd parity levels

“…In most cases, classical spectroscopy [8][9][10][11] or laser spectroscopy in a hollow cathode discharge (optogalvanic detection or laser-induced fluorescence (LIF)) was applied [12][13][14][15][16]. Spectral lines corresponding to these transitions are relatively strong and thermal population of the lower levels is usually strong enough to also apply laser spectroscopy on an atomic beam [17][18][19][20][21][22] or Doppler-free methods (e.g. saturation or intermodulation spectroscopy) in a hollow cathode discharge [23][24][25].…”

Techniques of laser spectroscopy in investigations of lanthanides’ free atoms and ions

“…2 and 3, and an example of the recorded hyperfine structure pattern for a spectral line in praseodymiumin Fig. 4 With the use of atomic beam systems available we measured the hyperfine structure of more than ten electronic levels in the lanthanum atom [1] and several tens of electronic levels in the praseodymium atom [2]. Fig.…”