Showing papers by "James Taylor published in 1983"
TL;DR: In this article, the angular distribution parameter as a function of photon energy is shown to be of value in the assignment of bands in photoelectron spectra and has been applied to the photo electromagnetic spectra of pyridine.
Abstract: Angle-resolved photoelectron spectra were obtained on a series of nitrogen-containing aromatic systems using synchrotron radiation as the ionizing source. The angular distribution parameter, ..beta.., was measured in the photon energy range 12-27eV for the first three orbitals of 2-fluoropyridine, pentafluoropyridine, and pyridine, and for the first four orbitals of pyrimidine and pyrazine. The angular distribution parameter as a function of photon energy is shown to be of value in the assignment of bands in photoelectron spectra and has been applied to the photoelectron spectra of pyridine. The fluoro-substituted pyridines provided information on the trend of the ..beta.. values for nonbonding orbitals with predominant nitrogen lone-pair character. The diazines demonstrated that ..beta.. values as a function of photon energy could be used for orbital assignments even in the case of partial band overlap. For pyridine the overlap of the first two ionic levels, consisting of a ..pi.. and a nonbonding orbital, is so severe that unambiguous assignment has been difficult but is now possible. Experimental evidence is presented for the sequence of these levels to be the nonbonding (n) orbital at lower ionization energy followed by the ..pi.. orbital. The relevance of systematic investigations of the angle-resolved photoelectron spectroscopy of amore » homologous series of molecules as a function of photon energy is discussed.« less
56 citations
22 Jun 1983
TL;DR: In this paper, the authors provide an overview of one school of thought in this area, typified by the following key ideas: 1. Quasilinear models of the nonlinear system that account for the operating range of system variables must be more realistic than conventional linear models. 2. The designer should be led to a nonlinear controller design if and only if it is really required.
Abstract: Recent research in the area of describing function approaches (both random-input and sinusoidal-input) has laid the foundation for a systematic approach to designing controllers for nonlinear plants. This paper provides an overview of one school of thought in this area, typified by the following key ideas: 1. Quasilinear models of the nonlinear system that account for the operating range of system variables must be more realistic than conventional linear models. 2. A staged design approach that applies more power to "difficult" nonlinear plants than to "easy" ones is more sensible than a single design method. 3. The designer should be led to a nonlinear controller design if and only if it is really required. These points will be developed, illustrated and justified in this presentation.
53 citations
TL;DR: In this paper, a program of accurate pulse arrival time measurements was initiated at the Arecibo Observatory, which were conducted at 1,408 MHz centre frequency, indicate that pulse arrival times follow a simple spindown equation with an accuracy of 1.5 µs for intervals between 2 min and 14 days.
Abstract: Following the discovery of the rapidly spinning pulsar 1937+214 on 7 November 19821 a program of accurate pulse arrival time measurements was initiated at the Arecibo Observatory. These observations, which were conducted at 1,408 MHz centre frequency, indicate that pulse arrival times follow a simple spindown equation with an accuracy of 1.5 µs for intervals between 2 min and 14 days. The apparent period derivative of 1.2 × 10−19 s s−1 leads to a characteristic tune scale P/Ṗ for period evolution of 4 × 108 yr. If the observed stability of this pulsar persists for decades, we will be able to reduce present uncertainties on the masses of the distant planets.
39 citations
TL;DR: The spectral range for passive mode-locking of flashlamp pumped dye lasers has been extended towards the blue (452 − 515 nm) by employing the saturable absorber 2-(p-dimethylaminostyryl)-pyridylmethyl iodide (DASPI).
11 citations
TL;DR: The viscocity-dependent fluorescence lifetime of some cyanine dyes with peak absorption cross-sections in the 350-500 nm range have been examined using a synchronously operating strek camera in conjunction with the picosecond excitation pulses from a frequency doubled synchronously pumped c.w. dye laser.
11 citations
TL;DR: In this paper, a synchroscan streak camera system was further developed to obtain both picosecond temporal resolution and direct photomultiplier read-out from a single image tube.
8 citations
TL;DR: A synchronously driven streak camera with stroboscopic deflection drive and detection provides picosecond time resolution with direct photomultiplier read-out over an extended free temporal range as mentioned in this paper.
8 citations
TL;DR: In this paper, measurements of the pertinent characteristics of a new saturable absorber dye (DASBTI) are presented, together with results which demonstrate its usefulness in the passive mode locking of several flash-lamp-pumped dye lasers operating within the 508-583 nm wavelength region.
Abstract: Measurements of the pertinent characteristics of a new saturable absorber dye (DASBTI) are presented, together with results which demonstrate its usefulness in the passive mode locking of several flash-lamp-pumped dye lasers operating within the 508-583 nm wavelength region.
6 citations
01 Mar 1983
TL;DR: In this article, the Photochron II streak tube has been developed for single-shot streak camera and shown to have a limiting time resolution of 0.9 ps when the cathodewas illuminated close to the long wavelength threshold in order to minimise the photoelectronransit -time dispersion.
Abstract: The salient design features of a version of the Photochron II streak tube having aninternal microchannel plate intensification stage are described. Experimental results arepresented to demonstrate that a streak camera incorporating this image tube has a temporalresolution tit ps in the synchroscan mode of operation and %4 ps in single -shot operation.IntroductionThe Photochron II streak tube' that was first described at the 11th International HighSpeed Photography Congress was developed primarily for use in a single -shot streak camera.It was subsequently demonstrated to have a limiting time resolution ti0.9 ps when the cathodewas illuminated close to the long wavelength threshold in order to minimise the photoelectrontransit -time dispersion.2 Although a time resolution of 2.5 ps has been achieved for thistype of tube in a repetitive (or Synchroscan) streak operation in conjunction with a CWmode -locked dye laser,3 we recognised that some redesign was necessary to ensure that theinstrumental function could be an optimum in this mode.This development of a synchronously- operating streak camera with picosecond or subpico-second resolution is of particular importance at present, because CW mode- locked lasersproduce the shortest, frequency- tunable light pulses currently available.3
4 citations
TL;DR: The design method is based on recent breakthroughs in describing function theory that uses a modern algebraic problem formulation to remove all previous nonlinear system restrictions and arrive at quasilinear models of the plant that will serve as a realistic basis for control system design.
4 citations
TL;DR: The second, fourth, sixth and tenth harmonics of the amplified output from a mode-locked Nd:glass laser have been generated in a cascaded process involving nonlinear crystals and inert gases as discussed by the authors.
TL;DR: A general stability test is described which may be employed in the analysis of all switched-capacitor filters of the lossless discrete integrator (LDI) type.
Abstract: A general stability test is described which may be employed in the analysis of all switched-capacitor filters of the lossless discrete integrator (LDI) type.