Einc einfache Apparatur wird beschrieben, die das Geschwindigkeitsspektrum der XH+-bzw. XD ' -1onen ails Ion-Molekel-Reaktionen des Typs X+ + H, (DJ --f XH+ + H (XD+ + D) zu messen gestattet, und zwar ohne Nachbeschleunigung der sekundiren Ionen. Die einfallenden X+-Ionen haben eine Bewegungsenergie zwischen 20 und 200 eV. Ferner werden die Geschwindigkeitsspektren berechnet, die nach verschiedenen StoBmodellen zu erwarten
Recently the authors reported the appearance of a temporary infrared absorption band in NaCl crystals when they were excited with l a s e r pulses in the F-band o r in the M-band /l/. It was interpreted a s optical absorption by bound polarons. Here the results a r e reported of similar measurements on KBr crystals. Commercial and laboratory grown KBr single crystals were irradiated with a Co order to obtain an F-centre concentration of 1 to 4x1Ol6 c m . The transient infrared absorption band was created and measured in two ways. On one hand, the same technique was used as described in /l/. The F-centres were excited with a ruby laser beam and the infrared transmission was measured transversally in the 0.23 t o 0.45 eV range before and immediately after excitation. 60 t-source in -3
Magnetic circular dichroism was measured in the U, bands in KCl, KBr, KI, RbBr, RbI, and CsI. By an analysis of the data using the method of moments the spin-orbit splitting of the excited states was determined. Absorption spectra of the U, centres in RbBr, RbI, CsBr, and CsI and some of the optical properties of these compounds are also reported.Magnetischer Zirkulardichroismus wurde an der U,-Bande in KCI, KBr, KJ, RbBr, R b J und CsJ gemessen. Durch eine Analyse der MeBergebnisse mit der Momentenmethode wurde die Spin-Bahn-Aufspaltung der angeregten Zustlinde bestimmt. Absorptionsspektren der U,-Zentren in RbBr, RbJ, CsBr und CsJ und einige optische Eigenschaften der Verbindungen werden ebenfalls mitgeteilt.
The dielectric losses of KBr single crystals doped with BaBr2 at different concentrations, both uncolored and additively colored, have been measured. A maximum in the dielectric loss versus frequency curve in the additively colored crystal was observed. This relaxation maximum was found to be due to the presence of Z2 centers. Some remarks are made concerning the activation energies involved.
The principal absorption bands induced by irradiation at liquid-helium temperature with x rays in CsBr crystals are the complex F band and two overlapping V bands at 435 and 497 m/*. In view of the dichroic properties of these V bands, the most obvious model seems to be a Br 2~ molecule -ion lying in the (100) directions. The two observed absorption bands would be due to two transitions in the same center. Regarding the bleaching properties, the F center cannot be the only color center responsible for the structure of the complex absorption band. Hypotheses are proposed about the interactions between the V and F centers.
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