Spectroscopy and applications of the 3 3Σ+ electronic state of 39K85Rb.

We report new results on the spectroscopy of the 3 (3)Σ(+) electronic state of (39)K(85)Rb. The observations are based on resonance-enhanced multiphoton ionization of ultracold KRb molecules starting in vibrational levels v'' = 18-23 of the a (3)Σ(+) state and ionized via the intermediate 3 (3)Σ(+) state. The a-state ultracold molecules are formed by photoassociation of ultracold (39)K and (85)Rb atoms to the 3(0(+)) state of KRb followed by spontaneous emission. We discuss the potential applications of this state to future experiments, as a pathway for populating the lowest vibrational levels of the a state as well as the X state.

Spectroscopy of the double minimum 3 (3)ΠΩ electronic state of 39K85Rb.

We report the observation and analysis of the 3 (3)ΠΩ double-minimum electronic excited state of (39)K(85)Rb. The spin-orbit components (0(+), 0(-), 1, and 2) of this state are investigated based on potentials developed from the available ab initio potential curves. We have assigned the vibrational levels v' = 2-11 of the 3 (3)Π1,2 potentials and v' = 2-12 of the 3(3)Π0(+/-) potential. We compare our experimental observations of the 3 (3)ΠΩ state with predictions based on theoretical potentials. The observations are based on resonance enhanced multiphoton ionization of ultracold KRb in vibrational levels v" = 14-25 of the a (3)Σ(+) state. These a-state ultracold molecules are formed by photoassociation of ultracold (39)K and (85)Rb atoms to the 5(1) state of KRb followed by spontaneous emission to the a state.

Spectroscopic investigation of the A and 3 1Σ+ states of 39K85Rb.

By using a combination of molecular beam (MB) excitation spectra and two distinct ultracold molecule excitation spectra (UM+ and UM-), we have assigned high vibrational levels of the A and 3 (1)Σ(+) states from absorption spectra of the mutually strongly perturbed A (1)Σ(+) - 3 (1)Σ(+) - 1 (1)Π - 2 (3)Σ(+) - b (3)Π states of ultracold (39)K(85)Rb molecules in the energy region between 15,116 and 16,225 cm(-1) above the minimum of the ground X (1)Σ(+) state. The ultracold molecules (UM+ and UM-) are formed by radiative decay following photoassociation (PA) to a specific level of the 3(0(+)) state (UM+) or to a specific level of the 3(0(-)) state (UM-). We observe that the A and 3 (1)Σ(+) states are observable in the UM+ spectra, but absent from the UM- spectra. This is explained by considering Hund's case (c) selection rules and transition dipole moments between the upper excited A (1)Σ(+) (2(0(+))) state and the three Ω components (0(+), 0(-), and 1) at the ground-state dissociation limit. We propose further investigations of the extended potential wells of the A and 3 (1)Σ(+) states by combining short-range MB excitation spectra in a narrow Franck-Condon (FC) window near R(e) of the X (1)Σ(+) state, and long-range UM (and PA) excitation spectra, which have much larger FC windows.

Spectroscopic analysis of the coupled 1(1)Π, 2(3)Σ+ (Ω = 0-, 1), and b(3)Π (Ω = 0±, 1, 2) states of the KRb molecule using both ultracold molecules and molecular beam experiments.

We report the spectroscopic characterization of excited electronic states of KRb by combining spectra from molecular beam (MB) experiments with those from ultracold molecules (UM) formed by photoassociation (PA) of ultracold atoms. Spectra involving the 1(1)Π, 2(3)Σ(+), and b(3)Π states in a strongly perturbed region have been identified. This approach provides a powerful method to identify the vibrational levels of the excited electronic states perturbed globally by neighboring electronic states. This is because the two sets of spectra from the UM and the MB experiments probe the same energy region from very different initial electronic states. The UM experiments utilize high v'' levels of the a(3)Σ(+) state with large internuclear separations, while the MB experiments utilize low v'' levels of the ground X(1)Σ(+) state with near-equilibrium internuclear separations. Only the Ω = 1 levels of the 2(3)Σ(+) and b(3)Π states are observed in the MB spectra, while the Ω = 0(-), 1 levels of the 2(3)Σ(+) state and the Ω = 0(±), 1, 2 levels of the b(3)Π state are observed in the UM spectra.

Effects of pier uplift and sliding isolation on seismic perfomance of highway bridges

The effects of pier uplift on sliding isolated highway bridges are studied for a symmetrical two-span continuous deck bridge. The seismic excitation uses the 1940 El Centro earthquake ground motion with a scaled peak ground acceleration 0.60g, which is comparable to the Caltrans bridge design spectra of 0.60g acceleration for rock. Pier uplift is found to enhance the effectiveness of sliding isolation for a highway bridge, especially for piers with inadequate lateral strength capacity. Elastic behavior of the pier is possible, while the seismic perfomance of a sliding isolated highway bridge is affected minimally by the pier uplift. These benefits are achieved with a relatively small amount pier uplifting.(AU)

Multi - option earthquake engineering education

In response to the varied problems, needs and issues in regards to earthquake engineering civil engineering professionals require a multi - option, multi . topic curricula in order to best educate them for seismic considerations. Washington University, Department of Civil Engineering has developed such a curricula using three vehicles : The tipical Master of Science, MS, (thesis required), a professional degree entitled Master of Structural Engineering - Earthquake Engineering Option, MSE, (seismic design project required) and a nontopical Earthquake Engineering Certificate, EEC, (cource work only), the EEC, 10 units (one unit = one semester hour), and the MSE, 31 units, are specifically designed to provide a broad - based, advanced education in the areas of dynamic analysis, design and retrofit, and seismic related social issues, whereas, the MS program is designed specifically for the individual's area of seismic research focus (AU)

Performance evaluation of wall - frame buildings with sliding isolation system

A continuum model representing wall-frame buildings with a sliding isolation system is proposed as a practical method in the stage of preliminary desing. Both the frame action an the shear wall action are accounter for through a single nondimensional parameter. The accuracy of the proposed model is confirmed by test result reported by other researchers. The parametric study shows that the performance of the sliding isolation system with a weak recentering mechanism is less afected by the shearflexural nature of the superstructutre. It is also noted that the model considering only the first model yields satisfactory results is the maximum displacement and the peak acceleration of the basemat are the major concern. The earthquake response spectrum a wall-frame structures considering more than three modes, as obtained using the proposed continuum model, result in more accurate for all peak values of interest (AU)