Doppler-free spectroscopy using magnetically induced dichroism of atomic vapor: a new scheme for laser frequency locking

We demonstrate a Doppler-free spectroscopic method that we test on ⁸⁷Rb and ⁸⁵Rb vapor. By using a magnetic field to induce a dichroism on the sample, we generate a dispersive signal with low background, which allows us to lock a diode laser even on small spectroscopic features. We elaborate the advantages of this simple and easy method by comparing it to other methods. Received 15 October 2002 Published online 17 December 2002     

Absorption of stopped π− in 59Co, 75As, 197Au and 209Bi investigated by in-beam and activation γ-ray spectroscopy

In-beam pionic X-ray and γ-ray spectra and activation γ-ray spectra following π^? absorption at rest in ⁵⁹Co, ⁷⁵As, ¹⁹⁷Au and ²⁰⁹Bi have been measured. The isotopic yield distributions and thus the (π^?, xnγp) reaction yields were determined. The mean numbers of emitted neutrons and protons are, respectively, 4.5 ± 0.2 and 1.48 ± 0.16 for ⁵⁹Co, 5.1 ± 0.3 and 1.02 ± 0.14 for ⁷⁵As, 6.6 ± 0.4 and 0.32 ± 0.14 for ¹⁹⁷Au, and 6.8 ± 0.4 and 0.37 ± 0.16 for ²⁰⁹Bi. The experimental results are compared with a pre-equilibrium exciton model calculation and proton-induced spallation reactions. High spin states in the residual nuclei were observed. For pionic X-rays absolute intensities of various transitions are given.     

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Untersuchung gestörter Winkelverteilungen an F19 in ferromagnetischen Gittern

The perturbation of the 197 keV transition angular distribution in F¹⁹ was investigated by time-dependent spin rotation measurements following excitation with a pulsed beam. The recoil implantation technique was used to determine the internal magnetic fields for F¹⁹ in Fe, Co and Ni lattices. The results are:H _HF(F¹⁹ in Fe)=+(95700±500) Oe,H _HF(F¹⁹ in Co)=+(59500±1500) Oe,H _HF(F¹⁹ in Ni)=?(21830±350)Oe. The temperature and field dependence of the effective fields was studied. Strong satellite fields due to lattice perturbations were detected. The half life and the gyromagnetic ratio of the 197 keV 5/2⁺ state in F¹⁹ were redetermined asT _1/2=(80.2±0.5) nsec andg=+1.436±0.007.     

A new approach to impedance atomic spectroscopy

Resonant laser-induced changes of the dielectric constant of atomic or molecular gases are detected as deviations in the oscillation frequency of a circuit including the sample itself as a component. Heterodyne detection allows high sensitivity. The new non-intrusive technique is demonstrated in the spectroscopic investigation of neon and sodium atoms.Work partially supported by ENEL under contract n. U 815     

Sulla propagazione di onde elettromagnetiche in una colonna di plasma cilindrica circolare indefinita,soggetta ad agitazione termica elettronica e a un campo magnetico assiale uniforme

Summary A study is made about the ways of propagation of electromagnetic waves in a cylindrical plasma column subject to termic and electronic agitation and to an axial uniform field; and it is put in evidence the possibility for four ways of propagation of waves according to the cylinder's axis. Then it is examined a particular case in which the ways of waves propagation are reduced to two.

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A Bruno Finzi nel suo 70^mo compleanno.

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Lavoro svolto nell'ambito del Gruppo di ricerca n. 3 del Comitato per la Matematica del C.N.R.

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Entrata in Redazione il 26 gennaio 1970.     

Das Strom-Spannungs-Widerstands-Ersatzschaltbild von Elektreten

For one-dimensional electrets there is set up a current-voltage-resistance equivalent circuit, the aim of which is to change the boundary value problem of electrostatics, that is the calculation of the electric fields in electrets from the electric and geometric data and the applied voltage into a problem of network analysis of a circuit consisting of ohmic resistances, current sources and voltage sources.      

Nonlocal surface plasmon spectrum in quantizing magnetic field: Surface Bernstein mode branch (n=2)

The nonlocal surface plasmon spectrum in a quantizing magnetic field perpendicular to the surface has been found to have branches analogous to ‘Bernstein’ modes near multiples of the cyclotron frequency. The n=2 nonlocal surface ‘Bernstein’ mode is evaluated for low wavenumber, incorporating Landau quantization effects for degenerate and nondegenerate cases.     

Brownian motion of 2D vacancy islands by adatom terrace diffusion.

We have studied the Brownian motion of two-dimensional (2D) vacancy islands on Ag(110) at temperatures between 175 and 215 K. While the detachment of adatoms from the island and their diffusion on the terrace are permitted in this temperature range, the periphery diffusion of single adatoms is prohibited. The present scanning tunneling microscopy results provide the first direct experimental proof that the Brownian motion of the islands follows a simple scaling law with terrace diffusion being the rate limiting process. The activation energy of the vacancy island motion is determined to 0.41 eV.