Submillimeter wave spectroscopy of XeH+ and XeD+

The J=0–1 rotational transition of XeH+ and the J=1–2 transition of XeD+, which both occur near 390 GHz, have been studied by microwave absorption spectroscopy. For each of these all nine naturally occurring stable isotopes of xenon were detected. The magnetic hyperfine structure for the 129Xe forms and the electric quadrupole–magnetic hyperfine structure of both 131Xe forms were fully resolved and analyzed to determine the CI and eQq0 constants. The scaled spin–rotation parameter CI/(gIB) is found to be practically identical in XeH+ and HI, as it is also in the isoelectronic pair KrD+ –DBr/HBr. The available magnetic field was too small to resolve the rotational Zeeman effect, but the rotational g factor of XeH+ was estimated from Zeeman broadening. The mass-independent Dunham parameters U01, ΔH01, and ΔXe01 were determined from the very accurate microwave frequencies combined with higher order Dunham coefficients from published Fourier-transform infrared (FTIR) spectroscopy of XeH+ . Although it was not practical to observe XeH+ or XeD+ in excited vibrational states, we were able to detect the J=0–1 (v=1) transition of ArD+ .