The puzzling hyper-fine structure and an accurate equilibrium geometry of succinic anhydride

The puzzling fine structure in the rotational spectrum of succinic anhydride is explained and a semiexperimental geometry calculated.

Untersuchung der Hyperfeinstruktur des 5s25d2D3/2-und 5s26d2D3/2-Terms im In I-Spektrum durch Resonanzstreuung von Licht im äußeren Magnetfeld / Hyper fine Structure Investigation of the 5s25d2D3/2- and 5s26d2Ds3/2-States of the ln I-Spectrum by Resonance Scattering of Light in an External Magnetic Field

Using an Indium atomic beam as absorber the resonance fluorescence of the transitions 5d2D3/2 - 5p2P1/2 (λ = 3039 Å) and 6d2D3/2-5p2P 1/2 (λ=2560 Å) was measured as a function of an external magnetic field. In both states two signals were observed at magnetic fields, where three level crossings occur. The observed line shape is discussed for the case of overlapping level crossing components with regard to radiation width and hyperfine structure splitting. The experimental results can be described by the following values for the lifetime τ and the hyperfine structure constants A and B : 5d2D3/2: | A|=(64.5±1.0) Mc/sec·gJ/0.8; B/A = - 0.59±0.17; τ = ( 7.0± 0.4) · 10-9 sec · 0.8/gJ ;6d2D3/2: | A | =(72.1 ±0.3) Mc/sec·gJ/0.8 ; B/A = - 0.47 ±0.05; τ = (25.5±1 ) ·10-9 sec-0.8/gJ . The values and the sign of the hyperfine structure constants indicate interconfiguration mixing.

Isotope shift and hyper fine structure in the spectrum of tin

Shifts between all the even isotopes of tin ( Z = 50) have been measured interferometrically, for enriched samples, in the line 3283 Å of the spectrum of Sn II. The h.f.s. and shifts relative to the even isotopes of two of the three odd isotopes have also been measured. The results are compared with those obtained by other workers on the tin lines 6454 and 5799 Å, (i) in order to obtain absolute values of the volume shift constant for the tin isotopes, which involves estimation of the specific mass shift in the lines, and (ii) to calculate the configuration mixing in some of the levels concerned. After allowing for normal mass effect only the measured shifts are: 112-114; 22.0 mK; 114-116, 21.9 mK; 116-118, 18.0 mK; 118-120, 18.4 mK; 120-122, 16.6 mK; 122-124, 11.7 mK; 116-117, 8.4 mK; 118-119, 2.4 mK. A hyperfine doublet was observed in 3283 Å for both 117 Sn and 119 Sn; the splittings are 153.6 and 162.3 mK respectively and are attributed to the lower level involved in the transition.

The hyper-fine structure of the arc spectrum, and the nuclear rotation of indium

The are spectrum of indium was investigated with the object of finding whether any of its lines possessed hyperfine structure, resulting from a quantized nuclear spin, and a corresponding magnetic moment of the nucleus. The spectrum of cæsium, which was investigated by the author, closely resembles that of indium, both spectra being peculiarly suitable for investigation in respect of hyperfine structure on account of their remarkable simplicity. In the case of cæsium it was found possible to resolve the structure arising from the S-levels, but not that due to the P-levels. In indium, however, it was hoped, on account of the far greater separation of the P-levels and the correspondingly greater interaction between the nuclear spin and the electron orbit, to achieve a resolution of the structure due to the P-levels. This was found possible. The apparatus used for high resolving power was a reflection echelon grating; the instrument was made of fused silica, platinized. It had 25 plates each 7 mm. thick. The grating was made by Adam Hilger, Ltd., and possessed its theoretical resolving power of about 800,000 at a wave-length of 4500 A. U. The mounting and method of using the echelon grating are fully described. The source of light was a cooled vacuum tube containing helium and indium chloride, excited with external electrodes by means of a high-frequency alternating current. The analysis of the structure of the lines shows that the nucleus must be assumed to possess one quantum of rotation. The comparison of the deduced structures of the P ½ and the P 3/2 levels agrees quantitatively with Fermi’s theory of the interaction of the nuclear and the electron spins.