Optical-optical double resonance spectroscopy of potassium

摘要

This thesis concerns the investigation of newly observed electronic states of K$sb2$ by using the optical-optical double resonance (OODR) method: six $sp1Delta$g states, five $sp1Sigmasbsp{rm g}{+}$ states, two $sp1Pi$g states, and three triplet gerade states.;With regard to $sp1Delta$g states, five bound nd$sp1Delta$g (n = 11-15) electronic states were reinvestigated by ionization detection using a homemade ultrasensitive space charge limited diode, which detects ion signals (presumably K$sbsp{3}{+}$ produced by associative ionization). Also the 3$sp1Delta$g state was newly observed. The molecular constants and the Rydberg-Klein-Rees (RKR) potential curves for these states were generated using the obtained molecular constants. Using these and previous results, the dissociation energies, additional binding energies and molecular constants due to the weakly bound Rydberg bonding $delta$g orbital were discussed. The dependence of the molecular constants on the principal quantum numbers for the bonding and antibonding orbitals and the quantum defects were also discussed. The adiabatic and diabatic dissociation limits for those states were given based on comparison with theoretical calculations.;The molecular constants of the previously unobserved 5, 6, and 9$sp1Sigmasbsp{rm g}{+}$ states of K$sb2$ were determined and the potential curves were also constructed using the RKR method. The unusual double minimum potential well of the 7$sp1Sigmasbsp{rm g}{+}$ state was constructed using the inverted perturbation approach.;The absolute vibrational numbering of the newly observed state 3$sp1Pi$g was obtained by comparing the calculated FC factors with the excitation intensities and resolved fluorescence spectra. The RKR potential curve, which covers about 70% of the potential well, was determined from the experimentally determined rotational (B$sb{rm v})$ and vibrational (G(v)) constants. The 4$sp1Pi$g state was newly observed and partially characterized.;In addition to the singlet gerade states, the $4sp3Sigmasbsp{rm g}{+}, 3sp3Pi$g and 2$sp3Delta$g states of K$sb2$ were studied by perturbation-facilitated OODR spectroscopy for the first time. The molecular constants and the RKR potential curves of those states were derived and compared with theoretical calculations. Finally, the observation of the lowest "dark" vibrational levels of the b$sp3Pisb{rm u}$ state by resolved fluorescence from the $2sp3Deltasb{rm g}$ state confirmed the absolute vibrational numbering of the b$sp3Pisb{rm u}$ state and allowed refinement of the b$sp3Pisb{rm u}$ molecular constants.