Molecular Beam Investigation of Rotational Transitions. II. The Rotational Levels of KBr and Their Hyperfine Structure

The molecular beam electrical resonance method has been used to study the hyperfine structure of the first rotational state in K³⁹{Br}⁷⁹$ and ${K}³⁹Br⁸¹.The hyperfine structure arises from the splitting of the $J=1$ state into 10 levels by the quadrupole interactions of potassium and bromine. Molecules in the $J=0$ rotational state were refocused, and transitions to the $J=1$ state were observed by a decrease in beam intensity at the surface ionization detector.From the structure of the line resulting from the transition J=0→J=1 in the three lowest vibrational states, the following results were obtained. The molecular constants are The quadrupole interactions and dipole moments in K³⁹{Br}⁷⁹$ in the $v=0, 1, 2$ vibrational states are The quadrupole interactions in the $v=0$ state of ${K}³⁹Br⁸¹ are (eqQ)K=-5.002±0.003 and (eqQ)Br=8.555±0.006 Mc/sec.The mass ratio of the bromine isotopes is M_Br⁷⁹M_Br⁸¹=0.9753088±0.0000020. The ratio of the bromine quadrupole moments is Q_Br⁷⁹Q_Br⁸¹=1.1973±0.0006.