Wei-Tzou Luh

Observation of the 39K2 a 3Σ+u state by perturbation facilitated optical–optical double resonance resolved fluorescence spectroscopy

Rydberg states of the potassium dimer in the 28u2009430–29u2009080 cm−1 and 30u2009030–30u2009500 cm−1 regions above the ground state X1Σ+g minimum have been studied using the perturbation facilitated optical–optical double resonance technique (PFOODR). Energy levels in these energy regions have been assigned to both triplet and singlet gerade states based on excitation pattern information as well as intensity considerations. Resolved fluorescence from a mixed triplet–singlet 43Πg ∼1Πg upper state to the ground triplet state au20093Σ+u has been used to construct a potential energy curve for the au20093Σ+u state which is in excellent agreement with recent theoretical results. Since this electronic state and the ground singlet state X1Σ+g share the same dissociation limit, we have determined the dissociation energy for the potassium dimer to be De=4450±2 cm−1.

Direct excitation studies of the diffuse bands of alkali metal dimers

Direct dye laser excitations of the K2 yellow, Rb2 orange, and Cs2 near‐infrared diffuse bands have been investigated. Experimental results are shown to be consistent with the assumed bound–free 2u20093Πg–1u20093∑+u excitations. It is found that for Rb2 and Cs2, spin–orbit interactions become so significant that the 2u20093Πg state is strongly split into three quite independent component states.

The X1Σ+, A1Π, and B1Σ+ potential energy curves and spectroscopy of BH

Abstract The RKR and hybrid potential energy curves have been constructed for the X 1 Σ + , A 1 Π, and B 1 Σ + states of BH. The radiative transition probabilities between the A 1 Π and X 1 Σ + states have also been obtained. The predicted laser-induced fluorescence spectra corresponding to one argon ion laser line coincidence and one krypton ion laser line coincidence are also presented for the A 1 Π → X 1 Σ + transition.

The A 1Σ+u state of the potassium dimer

Using resolved fluorescence from a 1Σ+g Rydberg state to the Au20091Σ+u state of K2, we have observed the lowest vibrational levels (v’≤12) of the Au20091Σ+u state. Levels v’=21 to 62 (well beyond the previously known v’=12 to 18 region) were observed using the polarization optical–optical double resonance technique. Molecular constants and a Rydberg–Klein–Rees (RKR) potential energy curve based on these constants are given. Franck–Condon factors for the K2, Au20091∑+u–Xu20091∑+g system based on this new Au20091Σ+u potential are also given.

Free-bound-free resonance fluorescence in the K2 yellow diffuse band: Theory and experiment☆

Abstract Free-bound-free resonance fluorescence of the K 2 yellow diffuse band directly excited by single mode dye lasers has been investigated. Quantum-mechanical treatments of this type of fluorescence are described. Simulation spectra with slightly shifted ab initio potentials have been calculated for both absorption and resonance fluorescence. In terms of relative intensities, rather satisfying agreements between observed spectra and their simulated counterparts have been obtained.

Interference continuum fluorescences of K2

Abstract K 2 interference continuum fluorescences were observed for the first time using irradiation by either an Ar + laser line at 457.9 nm or a Kr + laser line at 413.1 nm. Quantum-mechanical simulations clearly demonstrate that the fluorescence excited by 457.9 nm is due to the 2 1 Σ + u -X 1 Σ + g bound-free electronic transition.

Fluorescence of Na2 and K2 excited by a gold vapor laser

Abstract The gold vapor laser has been used to irradiate the alkali dimers Li2, Na2, K2, and Rb2. Significant fluorescence was found only from Na2 and K2. Six fluorescent series in the A1Σu+-X1Σg+ system of Na2 and three in the B1Πu-X1Σg+ system of K2 were assigned, respectively. New spectroscopic constants for the X1Σg+ state of 39K2 are derived, and new RKR potential energy curves for the X1Σg+ and B1Πu states of 39K2 are given.

New optically pumped lasers in the B1Πu-X1Σg+ and A1Σu+-X1Σg+ bands of Li2☆

Abstract Using an argon ion laser and a krypton ion laser operated in a single longitudinal mode, in conjunction with variations of the temperature of the heat-pipe ovens used and predictions of promising transitions with intensity calculations, we obtained 26 new optically pumped laser (OPL) series and 43, 34, and 53 new OPL lines of 6 Li 2 , 6 Li 7 Li, and 7 Li 2 , respectively, in the B - X and A - X band systems.

Studies of the Diffuse Bands of K2, Rb2 and Cs2

Direct dye laser excitations of the K2 yellow, Rb2 orange and Cs2 near infrared diffuse bands have been investigated. Experimental results are shown to be consistent with free‐bound 23πg←13Σ+u excitation followed by bound‐free emission between the same two states. It is found that Rb2 and Cs2, spin‐orbit interactions become so significant that the 23πg state is split into three component states. For Rb2, all three spin orbit components of the 23πg state are produced in direct excitation, whereas for Cs2, most excitation wavelengths produce only one of the three spin‐orbit components.

OODR fluorescence and polarization spectroscopy of K2: Rydberg states and the A1Σ+u state

We have observed K2 Rydberg electronic states of 1Δg and 1Σ+g symmetry using CW optical‐optical double resonance techniques in the energy range 28920–30050 cm−1 above the ground state minimum. Resolved fluorescence from the 1Σ+g states to the A1Σ+u state allows us to observe the lowest (v<12) vibrational levels of the A1Σ+u state. Using the polarization optical‐optical double resonance technique we are able to observe A1Σ+u vibrational levels in the range v=21 to 62. We are able to determine also the absolute vibrational numbering of one 1Δg Rydberg state. Major molecular constants are given for the 1Δg Rydberg state.