EPR of photochromic Mo3+ in SrTiO3

In single crystals of SrTiO_3, a paramagnetic center, characterized by S = 3/2 and hyperfine interaction with an I = 5/2 nuclear spin has been observed in the temperature range 4.2K-77K by means of EPR. The impurity center is attributed to Mo3+. No additional line splitting in the EPR spectrum due to the 105K phase transition has been observed. At 4.2K the following spin Hamiltonian parameters for this impurity ion were obtained: g = 1.9546\pm0.0010 and A = (32.0\pm0.05)\times10^-4 cm^-1.Comment: 5 pages, 2 figure

Fluorescence for high school students

In a not obligatory series of lessons for high school students in the Netherlands we discuss the fluorescence aspects of anthracene. These lessons were developed because HiSPARC (High school Project on Astrophysics Research with Cosmics) detection of cosmic rays are available for different secondary schools. With the help of special designed scintillator detection stations, containing anthracene, cosmic rays can be detected. Fluorescence of anthracene is one of the topics discussed in these series of extra curricular lessons aimed at excellent pupils working on cosmic radiation within the HiSPARC - project.Comment: 14 pages, 13 figures, 5 reference

Dutch corporate liquidity mangement: New evidence on aggregation

In this paper we investigate Dutch corporate liquidity management in general, and target adjustment behaviour in particular. To this purpose, we use a simple error correction model of corporate liquidity holdings applied to firm-level data for the period 1977-1997. We confirm the existence of long-run liquidity targets at the firm level. We also find that changes in liquidity holdings are driven by short-run shocks as well as the urge to converge towards targeted liquidity levels. The rate of target convergence is higher when we include more firm-specific information in the target. This result supports the idea that increased precision in defining liquidity targets associates with a faster observed rate of target convergence. It also suggests that the slow speeds of adjustment obtained in many macro studies on money demand are artefacts of aggregation bias.corporate liquidity demand, precautionary liquidity

Forecasting the money multiplier: implications for money stock control and economic activity

Forecasting ; Money supply

Calculation of the zero-field splitting D and g(perp)parameters in EPR for d3 spin systems in strong and moderate axial fields

Numerical and analytical methods are used to investigate the calculation of the zero field splitting |2D| and g(perp) parameters in EPR for octahedrally surrounded d3 spin systems (S = 3/2) in strong and moderate axial crystal fields (|D|>=h{\nu}). Exact numerical computer calculations are compared with analytical results obtained from third-order perturbation theory. From the analyses we conclude that EPR measurements performed at a single frequency with the magnetic field H at a magic angle {\alpha}_M, where 62deg < {\alpha}_M < 63deg, with respect to the axial crystal field of the d3 spin system, yields an almost exact solution in third-order perturbation theory. For dual frequency experiments, i.e. X-K, X-Q and K-Q band experiments, performed with the magnetic field H at an angle of {\alpha} = 90deg with respect to the axial crystal field, the ratio h\u{psion}/|2D| has to be smaller than 0.25 in order to use third order perturbation calculations within an error limit of 0.020% in the g(perp) values. For values of h\u{psion}/|2D| >= 0.25 one has to proceed with exact numerical computer calculations. Finally, we conclude that measurements performed at a single EPR frequency experiment with the magnetic field H directed along two specific angles with respect to the axial crystal field of the octahedrally surrounded d3 centre, i.e. {\alpha} = 90deg and {\alpha} = 35deg16 respectively, third-order perturbation theory gives non-reliable results for the |D| and g(perp)-values.Comment: 9 pages, 2 figure