Purely rotational coherence effect and time-resolved sub-Doppler spectroscopy of large molecules. I. Theoretical

In this and the accompanying paper we present a theoretical treatment and experimental study, respectively, of the phenomenon termed purely rotational coherence. This phenomenon has been demonstrated to be useful as a time domain means by which to obtain high resolution spectroscopic information on excited state rotational levels of large molecules [Felker et al., J. Phys. Chem. 90, 724 (1986); Baskin et al., J. Chem. Phys. 84, 4708 (1986)]. Here, the manifestations in temporally resolved, polarization-analyzed fluorescence of coherently prepared rotational levels in samples of isolated symmetric and asymmetric top molecules are considered. These manifestations, for reasonably large molecules at rotational temperatures characteristic of jet-cooled samples, take the form of polarization-dependent transients and recurrences with temporal widths of the order of tens of picoseconds or less. The transients, which arise from the thermal averaging of many single molecule coherences, are examined with respect to their dependences on molecular parameters (rotational constants, transition dipole directions) and experimental parameters (polarization directions and temperature). A physical picture of rotational coherence as a reflection of the time-dependent orientation of molecules in the sample is developed. And, the influence of rotational coherence in experiments designed to probe intramolecular energy flow is discussed. In the accompanying paper, we present experimental results for jet-cooled t-stilbene and anthracene. For t-stilbene we determine rotational constants for vibrational levels in the S1 electronic state (from the recurrences) and we monitor the trends in rotational coherence vs vibrational coherence as the total energy in the molecule increases

Laser phase modulation approaches towards ensemble quantum computing

Selective control of decoherence is demonstrated for a multilevel system by generalizing the instantaneous phase of any chirped pulse as individual terms of a Taylor series expansion. In the case of a simple two-level system, all odd terms in the series lead to population inversion while the even terms lead to self-induced transparency. These results also hold for multiphoton transitions that do not have any lower-order photon resonance or any intermediate virtual state dynamics within the laser pulse-width. Such results form the basis of a robustly implementable CNOT gate.Comment: 10 pages, 4 figures, PRL (accepted

Picosecond excitation of jet-cooled hydrogen-bonded systems: Dispersed fluorescence and time-resolved studies of methyl salicylatea

Long progressions involving frequency intervals of 180 cm^(−1) are observed in the fluoresence of MS for 3327.5 Å excitation. (AIP

Observation of intracavity absorption of molecules in supersonic beams

Intracavity absorption studies of DMT and I2 are reported at rotational and vibrational temperatures of <0.1 K and 16 K, respectively

Design and Implementation of an Automated Pick and Place System for Johanson Technology, Inc.

Johanson Technology, a capacitor and microelectronic part manufacturer, located in Camarillo, CA has forecasted a 50% increase in demand for single layer capacitors for the year 2011. Johanson chose to hire an intern to design and implement a robotic pick and place system to meet this demand. A complete automated system composed of a Stäubli RS20 robotic arm, CS8C-M Controller, and Electrosort Bowl Feeder needed to be integrated into an environment where no system currently existed. A bill of materials and parts list indicated that the entire system would be a fixed cost of $50,104. This proved to be the superior choice over the alternatives of hiring an outside consultant to design the system for$115,051 or hiring an additional employee to hand pick and place the parts for nearly $24,000 annually. Programs were written in VAL3, Stäubli’s own programming language, for the RS20 to pick and place parts in a grid formation onto Waffle, Gel, and Ring Packs. A custom tool composed of manufactured and purchased parts was made at Johanson Technology and held by the RS20 arm to handle the single layer capacitors. Performance of the system’s placement accuracy was analyzed by measuring correct placements on Waffle, Gel, and Ring Packs. Waffle Packs received a placement accuracy of 99.21%, missing around 10-20 parts out of 2,400. Gel Packs received 99.71% accuracy, and Ring Packs failed to place parts consistently within their 2-3⁰ rotation tolerance so their accuracy of placement could not be measured. The robotic pick and place system places single layer capacitors into Waffle, Gel, and Ring Packs at two to three times the speed of a human operator. At this rate, Johanson Technology will be able to meet their demand

Performance and loads data from a hover test of a full-scale XV-15 rotor

A hover test of a full-scale XV-15 rotor was conducted at the Outdoor Aerodynamic Research Facility at Ames Research Center. The primary objective of the test was to obtain accurate measurements of the hover performance of the original, metal-blade XV-15 rotor system. Data were acquired for rotor tip Mach numbers ranging from 0.60 to 0.73. This report presents data on rotor performance, rotor wake downwash velocities, and rotor loads

Evaluating dictation task measures for the study of speech perception

This paper shows that the dictation task, a well- known testing instrument in language education, has untapped potential as a research tool for studying speech perception. We describe how transcriptions can be scored on measures of lexical, orthographic, phonological, and semantic similarity to target phrases to provide comprehensive information about accuracy at different processing levels. The former three measures are automatically extractable, increasing objectivity, and the middle two are gradient, providing finer-grained information than traditionally used. We evaluate the measures in an English dictation task featuring phonetically reduced continuous speech. Whereas the lexical and orthographic measures emphasize listeners’ word identification difficulties, the phonological measure demonstrates that listeners can often still recover phonological features, and the semantic measure captures their ability to get the gist of the utterances. Correlational analyses and a discussion of practical and theoretical considerations show that combining multiple measures improves the dictation task’s utility as a research tool

Wing force and surface pressure data from a hover test of a 0.658-scale V-22 rotor and wing

A hover test of a 0.658-scale V-22 rotor and wing was conducted in the 40 x 80 foot wind tunnel at Ames Research Center. The principal objective of the test was to measure the surface pressures and total download on a large scale V-22 wing in hover. The test configuration consisted of a single rotor and semispan wing on independent balance systems. A large image plane was used to represent the aircraft plane of symmetry. Wing flap angles ranging from 45 to 90 degrees were examined. Data were acquired for both directions of the rotor rotation relative to the wing. Steady and unsteady wing surface pressures, total wing forces, and rotor performance data are presented for all of the configurations that were tested

The influence of stock plant fertilization on tissue concentrations of N, P and carbohydrates and the rooting of Prosopis alba cuttings.

Clonal propagation techniques are required for Prosopis due to great variability in biomass productivity, pod productivity, and nitrogen fixation from seed propagated stock. Previous studies identified a decline in the rooting percentage of cuttings taken from stock plants that were grown in the growth chamber and harvested every four weeks. To determine the influence of the mineral nutrient status of the stock plants on the rooting of cuttings, fertilized and nonfertilized Prosopis alba clone B2B50 stock plants were established under 1000 W metal halide lamps in the greenhouse. A complete macro- and micronutrient solution was used. The regrowth was harvested after 4, 8, 12, 16, and 20 weeks, and alternate nodes from each stem were taken for the rooting assay and for N, P, K. Ca, Mg, Fe, Zn an total available carbohydrate evaluation (N=79). The mean rooting percentage for the five harvest cycles was 58% for the fertilized stock plants, and 44% for the nonfertilized stock plants (P=0.087). There was no significant correlation between rooting percentage and leaf carbohydrate (P=0.964), stem carbohydrate (P=0.876) and leaf plus stem phosphorus (P=0.319). The monsignificant correlation between percent rooting and carbohydrates was negative (r=-0.018). However, there was a significant correlation with stem nitrogen and percent rooting (P=0.009) and inverse correlation between sten nitrogen and leaf carbohydrate content (r=-0.353, P=0.001). This suggests that unbalanced fertilizers, rich in nitrogen (...)

Dynamics of intramolecular vibrational-energy redistribution (IVR). III. Role of molecular rotations

Experimental results on jet-cooled anthracene pertaining to the role of rotations in IVR processes are presented. For theoretical comparison, we consider the effects of molecular rotational level structure on the beat-modulated decays that arise as manifestations of IVR. It is shown theoretically for anharmonic coupling that small differences in rotational constants between coupled vibrational states give rise to decays, the beat envelopes of which decay faster than the unmodulated portions of the decays. These envelope decay rates are shown to be rotational temperature dependent. The experimental results reveal behavior entirely consistent with the theoretical expectations. The results also show that although rotational effects are present in experimental decays, they are not so marked as to wash out the manifestations of vibrational coherence