The physical properties of linear chain systems. I. The optical spectra of [(CH3)4N]NiCl3, Cs(Mg,Ni)Cl3, CsNiCl3, RbNiCl3 and CsNiBr3

The single crystal spectra of pure CsNiCl₃, CsNiBr₃, RbNiCl₃, and [(CH₃)₄]NiCl₃, and the single crystal spectrum of CsNiCl₃ diluted in CsMgCl₃ have been measured to 5°K. The spectra of the magnetically concentrated materials show a number of anomalously intense maxima. These are interpreted in terms of cooperative interactions.     

Absorber-induced features in the ac response of a He-Ne laser

The theoretically predicted pronounced ac-response of the laser intensity to the excitation current modulation of an intracavity saturable absorber has been experimentally verified in a He-Ne laser with a Ne-absorber. Good qualitative agreement with the theory is obtained.     

A CNDO/2 calculation on stilbene

The equilibrium conformations of trans- and cis-stilbene and the rotational barrier between the two isomers were calculated using the CNDO/2 method. The results for the equilibrium angles and distances are in good agreement with experimental data. However, according to the calculations the phenyl rings would have a nearly free rotation which is only limited by steric hindrance. This result obviously deviates from the current view. The results are discussed in relation to previous theoretical and experimental evidence.

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Zusammenfassung Die Gleichgewichtskonformation von trans- und cis-Stilben und die Rotationsbarriere zwischen zwei Isomeren wurde nach der CNDO/2-Methode berechnet. Die Ergebnisse in bezug auf die Geometrie stimmen mit experimentellen Daten gut überein, die Rotationsbarriere für die Drehung der Phenylringe dagegen ist praktisch Null.

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Résumé La méthode CNDO/2 a été employée pour calculer les conformations d'équilibre du trans- et du cis-stilbène ainsi que la barrière de rotation entre ces deux isomères. Angles d'équilibre et distances calculés sont en bon accord avec les données expérimentales. Cependant les calculs indiquent que les cycles phényles devraient posséder une rotation libre soumise seulement à l'empêchement stérique. Ce résultat s'écarte de l'opinion courante. Les résultats sont discutés en relation avec les données théoriques et expérimentales antérieures.

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This work was supported by grant No 2741-4 from The Swedish Natural Science Research Council and grant No 69-927/U 697 from The Swedish Board for Technical Development.     

Styrene and polystyrene microemulsions. I. Solubility in the W/O system

The solubility of styrene, its oligomers, and different molecular weight polymers was determined in W/O microemulsions stabilized by sodium dodecyl sulfate and pentanol. The results showed a complex pattern due to the interactions with pentanol, surfactant, and associated structures.     

Public Expenditure Forecasting and Control — The Practical Use of Distributed Lag Models

There are several reasons why expenditure managers need to forecast the financial progress of programmes accurately. The paper discusses the use of distributed lag models to assist in this and the practical decisions required in the process of selecting, setting up and calibrating the models.     

Cathodoluminescence in deformed MgO crystals

The corrected cathodoluminescence (CL) emission spectrum for undeformed MgO in the wavelength range 300–650nm consists of two overlapping bands with peaks at 425 nm (2.92 eV) and 488 nm (2.54 eV). After deformation one broad band at 466 nm (2.66 eV) of much higher intensity is observed. In the near IR part of the spectrum a further broad band occurs, consisting of a number of unresolved peaks the strongest of which is at 726 nm (1.71 eV). This band is unaffected by deformation and is thought to be due to iron impurities. Panchromatic and monochromatic SEM micrographs show that the enhanced 466 nm band luminescence comes from the slipped planes of the crystal. Shape analysis of the 466 nm emission band showed that it is a Gaussian form around the intensity maximum with an exponential high energy tail.     

Implementation of chebyshevian linear multistep formulas

A Chebyshevian linear multistep formula is a formula fitted to a Chebyshev set of basis functions. This paper presents a unified approach for the implementation of Chebyshevian backward differentiation and Adams formulas for solving ordinary differential equations. The approach is based on generalized scaled differences, derived from generalized divided differences, and it includes the generalized Newton interpolation formula as predictor for the Chebyshevian implicit backward differentiation formula and Chebyshevian Adams-Bashforth-Moulton formulas. The local truncation errors are estimated by means of the scaled differences providing information for the control of order and steplength.     

Redistribution of molecular velocities by optical processes

In this paper we formulate the theory of spontaneous decay with recoil included. The vacuum is treated as a reservoir absorbing the spontaneously emitted photons. This assumes no correlation between consecutive emission events and zero probability of photon reabsorption. The spontaneous emission is assumed independent of the strong fields present. Some simple consequences of the theory are discussed. We solve the two-level system with one strong running wave and plot the velocity distribution of the two levels. We find modifications both of the average velocity and the line shapes. In particular the lower level Bennett hole experiences a narrowing in certain parameter ranges.