ALBERT

Notes: Doppler-free high resolution spectrum of the B 1Π(v',J')–X 1Σ+(v‘,J‘) transitions of 23Na39K was measured by the optical–optical double resonance (OODR) polarization spectroscopy. The transition lines up to the v'=43 level, which was estimated to be 1.8 cm−1 below the dissociation limit, were observed. The potential energy curve for internuclear distance from 3.25 to 15.6 A(ring) was calculated by the RKR method, and the inverse-power coefficient was determined by analyzing the long-range RKR turning points. The B 1Π state dissociates to Na(3s2S1/2)+K(4p2P3/2) atoms without a potential hill near the dissociation limit. The dissociation energy was determined to be 1324.3±0.3 cm−1 from the LeRoy–Bernstein plots. Remarkable line broadenings were observed for transitions higher than the dissociation energy to Na(3s2S1/2)+K(4p2P1/2) atoms. This is identified as originating from the predissociation to Na(3s2S1/2)+K(4p2P1/2) atoms. The predissociation is shown to be caused by a spin–orbit interaction between the B 1Π and (2)3Σ+ states, and the potential curves are expected to cross around the inner turning point of the B 1Π (v'=34) level.

Notes: Transitions from the A 1Σu+ (v=4, J=11 and 9) level to the F 1Σg+ (v=3, J=10) and 2 1Σu+ (v=2, J=10) levels of the 6Li7Li molecule, were observed using Doppler-free two-step polarization labeling spectroscopy. The intensity ratio of the two transitions was approximately 150:1. The energy spacing between the deperturbed F 1Σg+ (v=3, J=10) and 2 1Σu+ (v=2, J=10) levels was calculated to be 0.11 cm−1. The 2 1Σu+←A 1Σu+ transition becomes allowed due to an interaction between gerade and ungerade states resulting from the mass difference of the nuclei. The interaction energy between the F 1Σg+ (v=3, J=10) and 2 1Σu+ (v=2, J=10) levels was calculated to be 0.009 cm−1 from an analysis of the deperturbed level energies and the ratio of the line intensities. © 2001 American Institute of Physics.

Notes: The excitation spectrum of the Cs2 molecule monitoring the emission from the dissociated Cs(6p2P3/2) atoms was measured by employing a pulsed supersonic molecular beam crossed with a laser beam. Strong predissociation was found in the 16 600–17 200 cm−1 region. Vibrational progressions with broad asymmetric profiles, which were found via the ionization of dissociated Cs(6p2P3/2) atoms by Kim and Yoshihara, were observed. Transitions from the ground state X 1Σg+ to the dissociative state (2)3Σu+ are allowed by the spin-orbit interaction between the (2)3Σu+ and B 1Πu states. The (2)3Σu+, (2)3Πu, and C 1Πu states are mixed by the spin-orbit interaction. By solving the coupled differential equations using the three-channel model, the transition probability to the mixed levels, (2)3Πu(v) and C 1Πu(v′) was calculated. The coupling between the (2)3Σu+ and (2)3Πu states is larger than that between the (2)3Σu+ and C 1Πu states. Accordingly, the linewidth of the (2)3Πu←X 1Σg+ transition is observed to be wider than that of the C 1Πu←X 1Σg+ transition. The sign of the Fano shape index q was shown to coincide with the sign of the vibrational overlap integral between the discrete level and the continuum. © 2000 American Institute of Physics.

Notes: The excitation spectra of the 15V 31 344.9 band of the CS2 V 1B2←X 1Σg+ transition and the changes in these spectra with the application of a magnetic field of up to 12 kG have been measured with sub-Doppler resolution. The radiative lifetimes of rotationally resolved single lines and single Zeeman components were measured under collision-free conditions. All of the fluorescence decays were observed to be of a single exponential. Large Zeeman splittings were observed for many lines. The only symmetry allowed spin–orbit interaction is that of the 3A2(B2) component with the 1B2 state. The 3A2(B2) component has no magnetic moment, but a magnetic moment is induced when it is mixed with the 3A2(A1,B1) components. The mixing of the 3A2(B2) and 3A2(A1,B1) components is facilitated by spin–rotation interaction and the Zeeman interaction. From analysis of the observed Zeeman splittings of the perturbed levels, the 3A2(B2) component was determined to lie 14 cm−1 below the nearly degenerate 3A2(A1) and 3A2(B1) components in the energy region where the 15V band is observed. Irregular energy shifts and splittings of rotational lines were observed, and these were attributed to (a) Coriolis interaction between the V1B2(v′(a1);K=0JM) and V 1B2(v(b2);K=1JM) levels and (b) resonant spin–orbit interaction between the rotational levels V 1B2(v′(a1);KJM) and R 3A2(v(a1);KJM). These interactions become appreciable when two levels lie close in energy. Large Zeeman splittings were observed in case (b). Many vibrational lines with irregular intensity and spacing were observed in each band. These were attributed to (c) Fermi resonance between the vibrational levels in the V 1B2 state and (d) resonant spin–orbit interaction between vibrational levels in the V 1B2 and R 3A2 states. In case (d), large Zeeman splittings were observed for a series of rotational lines in a vibrational band. The background lines were identified from observed Zeeman splittings as the transitions to levels of the R 3A2 state, which are induced by resonant spin–orbit interaction with the levels of the V 1B2 state. The intensity of the excitation spectrum of the V 1B2←X1Σg+ transition was observed to decrease as the magnetic field increases. This was attributed to a mixing of the 3A2 state with the V 1B2 state and the resulting triplet–triplet emission, which was not detected in this experiment. It was possible to evaluate the lifetime of the radiative triplet–triplet emission via deperturbation analysis of the perturbed lines. © 2000 American Institute of Physics.

Notes: Doppler-free UV-visible optical–optical double resonance polarization spectra of the 2 1Σu+←X 1Σg+ and C 1Πu←X 1Σg+ transitions in 7Li2 molecules were measured. In the case of the double minimum 2 1Σu+ state transitions to all vibrational levels (except the lowest two) localized in the inner potential well, to several levels in the outer well and some levels beyond the potential barrier were observed. Potential energy curves of the C 1Πu(v=0–10) state and the inner well of the 2 1Σu+ state are determined by the RKR method. A V(R) curve describing the whole potential of the 2 1Σu+ state (including both wells) is constructed using the Inverted Perturbation Approach (IPA). Tunneling splittings and energy shifts of the 2 1Σu+ levels were observed, and their magnitudes are well represented in a semiclassical model using the IPA potential. Perturbations between the C 1Πu(v,J) and 2 1Σu+(v′,J) levels were detected in the region above the potential barrier of the 2 1Σu+ state, where the rotational constant of the 2 1Σu+ state is much smaller than that of the C 1Πu state. © 2000 American Institute of Physics.

Notes: High resolution spectra of the 1 1Π(v′=13–69,J′)←X 1Σ+(v″,J″) and 2 1Π(v′=0–13,J′)←X 1Σ+(v″,J″) transitions of the 39K85Rb molecule have been measured with the technique of Doppler-free optical–optical double resonance polarization spectroscopy (OODRPS). Molecular constants of the 1 1Π(v=13–69) and 2 1Π(v=0–13) levels have been determined, and potential energy curves constructed by the RKR method. The RKR potential of the 1 1Π state was found to have a distortion at outer wall, which originates from an avoided crossing of two 1Π states. The perturbations between the 1 1Π(v1,J) and 2 1Π(v2,J) levels were found from the energy shifts of the rotational levels. The magnitude of the nonadiabatic interaction between the 1 1Π(v1=54) and 2 1Π(v2=9) levels, 〈1 1Π(v1=54)|TN|2 1Π(v2=9)〉, was evaluated to be 2.2 cm−1 by a least squares fitting to the energy shifts of the 1 1Π(v1=54,J=20–33) levels. The line intensities were observed to change dramatically around the maximum energy shift. These intensity anomalies are interpreted as an interference effect, which occurs when two interacting levels have comparable transition moments. A remarkable line broadening was observed for the transitions to the 1 1Π(v≥63) levels, and it was identified as originating from the predissociation to K(4s2S1/2)+Rb(5p2P1/2) atoms. The dissociation energies of the X 1Σ+, 1 1Π, and 2 1Π states have been determined to be 4217.4±0.8, 2021.5±0.8, and 1050.0±0.8 cm−1, respectively. © 1999 American Institute of Physics.

Notes: A Doppler-free polarization spectrum of the D 1Σ+u(v',J')–X 1Σ+g(v‘,J‘) transition has been observed, and the molecular constants of the D 1Σ+u state were determined. A remarkable variation of the vibrational spacing ΔGv with v', and large deviations of ΔGv from the fitted ΔGv curve for v'(approximately-greater-than)35 were analyzed. The potential curve of the perturbing state, which was identified as the bound (2)3Πu state, was estimated. By using an experimental setup where a collimated cesium beam is crossed at right angles by the laser beam, we measured the excitation spectra by monitoring separately the molecular fluorescence and the D2 or D1 atomic emission. We found that a predissociation of the D 1Σ+u state occurred for v'(approximately-greater-than)20, and the probability of predissociation increased with v'. The measured v' and J' dependence of the linewidth Γ showed a significant increase for v'(approximately-greater-than)25. The predissociation of the D 1Σ+u state is caused by a combination of spin–orbit interaction between the D 1Σ+u(v'J') and (2)3Π0u(e vJ') levels, and the L-uncoupling interaction between the bound (2)3Π0u(e vJ') and dissociative c 3Σ+u(N = J'J') levels.

Notes: A photoeletronic bistable device with selectable light output channels has been fabricated for implementation in photonic switching and processing systems. The device is a variation of the vertical to surface transmission electrophotonic device. Output in the stimulated light emission mode was successfully obtained from different waveguide channels by external electronic switching. Output channels could be switched at a rate of 400 Mb/s. The potential versatility of this device has been experimentally confirmed in programmable or switchable optical interconnections.

Notes: Surface emitting optical devices with a vertical cavity have been investigated for applications in optical interconnections. To integrate these devices into a two-dimensional array, it is necessary to improve the conversion efficiency from electrical power to optical power. To meet this requirement, the series resistance of the distributed Bragg reflectors that form the vertical cavity must be reduced. This article demonstrates the reduction in the series resistance of the distributed Bragg reflector by introducing quasi-graded superlattices at the heterointerfaces. By using this structure, we obtain a low series resistance distributed Bragg reflector without compromising the high reflectivity. The mechanism of the reduction in the series resistance is studied and it is found that an increase in tunneling current leads to a decrease in the resistance. The dependence of tunneling current on doping concentration of the distributed Bragg reflector and the superlattice structure is also discussed.

Notes: The Doppler-free high resolution spectrum of the transitions to highly excited states of the 23Na39K molecule was measured by using the technique of the optical–optical double resonance polarization spectroscopy. Several highly excited states 1Σ+, 1Π, and 1Δ were found, and the molecular constants for these states were determined. The vibrational numbering of the 1Δ state (G 1Δ state) was estimated, and the potential energy curve was calculated by the Rydberg–Klein–Rees method. Many perturbed lines were observed. The indirect perturbation between 1Σ+ and 1Δ levels through the L-uncoupling interaction with a distant 1Π state was identified. The hyperfine splittings were observed in transition lines to a 3Π state, which is perturbed by a 1Σ+ state.