Knowledge Bank

A phase-stabilized backward wave oscillator (BWO) in the $260-380$ GHz range was combined with an XUV laser system to record high-resolution spectra of high Rydberg states of krypton. The millimeter wave transitions between high n Rydberg states were detected by pulsed field-ionization, at sub-MHz resolution. Results are presented on the hyperfine structure of high n Rydberg states of $\mathrm{<mrow\; data-mjx-texclass="ORD">83</mrow>}Kr$.