High-resolution vacuum–ultraviolet and ultraviolet photoionization spectroscopy of krypton

Accurate spectroscopy of krypton is performed on five transitions from the (4p6) 1S0 ground state to the 5d[1/2]1, 6s[3/2]1, 5p[1/2]0, 5p[3/2]2 and 5p[5/2]2 excited states (j l-coupling notation) by means of 1VUV + 1UV and 2UV + 1UV resonance-enhanced photoionization. Isotope shifts of all six stable isotopes are determined, and a King plot analysis indicates a large field shift factor even for transitions in which no s electron is involved. Absolute frequency calibration is performed on three transitions, leading to a novel determination of the excited state energies of Kr with an accuracy of ∼0.0013 cm−1. An accurate value for the ionization energy of 86Kr, 112 914.516(14) cm−1, is derived along with ionization energies for all even isotopes. The ac Stark effect on the two-photon transition to the 5p[1/2]0 excited state is investigated. For light intensities up to ∼260 MW cm−2 a linear shift of 0.75(48) Hz (W cm−2)−1 is observed, while at higher intensities the line exhibits a sub-linear shift and an asymmetric broadening. Consequences of the results obtained for the 5p[1/2]0 state on resonance-enhanced narrow-band XUV/VUV generation are discussed. 1