MOLECULAR BEAM MEASUREMENT OF THE HYPERFINE STRUCTURE OF TIBr.

This research was supported in part by the U.S. Atomic Energy Commission. $^{1}$ J. C. Zorn, T. C. English, J. T. Dickinson, and D. A. Stephenson, J. chem., Phys. 45, 3731 (1966). $^{2}$ H. G. Fitzky, Z. Physik 151, 351 (1958).Author Institution: Randall Laboratory of Physics, The University of MichiganWe have measured radiofrequency transitions between h\'{i}s levels in the $J = 2$ and $J = 3$ states of TlBr. The measurements were made with a molecular beam electric resonance $spectrometer^{1}$ under conditions of very weak electric and magnetic fields. From the observed frequencies we have calculated the hyperfine interaction constants for the ground vibrational state of $^{205}Tl^{79}Br$ and $^{205}Tl^{81}Br$. These are; $\begin{array}{lrc}&^{205}T\ell^{79}Br & ^{205}T\ell^{81}Br\\eqQ_{Br} & 126.31 \pm 0.1 &105.52\pm0.1\, MHz\\c_{Br}&3.72\pm0.5 & 3.96\pm0.5\,kHz\\c_{TI} & 42.75\pm0.5 &42.57\pm0.5\,kHz\\c_{3}&-1.59\pm2.0&-1.74\pm2.0\,kHz\\c_{4} & -6.37\pm 2.0 & -7.23\pm2.0\, kHz\end{array}$ where $eqQ_{Br}$ is the quadrupole coupling constant for the bromine nucleus, $C_{Br}$ and $C_{Tl}$ are the spin-rotation coupling constants for the bromine and thallium nuclei, respectively, and $C_{3}$ and $C_{4}$ are the coupling constants for the tensor and scalar parts of the nuclear spin-spin interaction. The values of $eqQ_{Br}$ are in agreement with, but more precise than those obtained by $Fitzky^{2}$ with microwave absorption spectroscopy. The magnetic coupling constant had not been measured previously. Measurements are being continued on the $J = 1$ and $J>3$ states, the excited vibrational states, and on the accompanying lines for the $^{203}Tl$ isotope. Work of the same nature is being done on TlI, but analysis of the observed spectrum is still in progress