Knowledge Bank

We have used our high resolution molecular beam electric resonance spectrometer to carefully examine the hyperfine spectrum of $Na18$Br in vibrational states v=0-5 and rotational states J=2-5. A total of 71 transition frequencies have been measured, most with a precision of 1-10 Hz. These can be fit with a reduced chi-square of only 1.23 by using 21 parameters expressing the vibrational and rotational variation of seven interactions including a magnetic octupole interaction for the bromine nucleus. Without inclusion of this interaction the observed frequencies of certain lines in the J=5 spectrum are inconsistent with predictions from other rotational states, with displacements of about 30 Hz. The interactions evaluated in this experiment have the values (all in units of kHz): \begin{eqnarray*} &&eQq (Br) =(48026.835 \pm .008) + (967.041 \pm .012)(v+1/2) -(9.796 \pm .005)(v+1/2)^{2} +\ &&\qquad(0.236 \pm .0006) (v+1/2)^{3} + (.3742 \pm .0004)J (J+1) - (.0054 \pm .0002)J (J+1)(v+1/2)\ &&eQq(Na) = -(4932.79 \pm .03) + (43.60 \pm .03)(v+1/2) - (.177 \pm .014)(v+1/2)^{2} +\ &&\qquad (0 \pm .002) (v+1/2)^{3} + (.017 \pm .002)J (J+1) +(.0020 \pm .0011)J (J+1)(v+1/2)\ &&C(Br) = (.3352 \pm .0002) + (.00670 \pm .00011)(v+1/2)\ &&C(Nr) = (.6799 \pm .0007) -(.0058 \pm .0003)(v+1/2)\qquad\qquad C_{4} = (.0905 \pm .0009)\ &&C_{3} = (.4220 \pm .0007)- (.0041 \pm .0002)(v+1/2) \qquad\qquad\Omega \omega (for J=5) = (.0031 \pm .0003). \ \end{eqnarray*} Observations consistent with the above have also been made for $Na79Br$. Work supported by a Northwest Area Foundation Grant of Research Corporation and NSF RUI Grant $\ne$ PHY-8319293.