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Linear dichroism (LD) spectra are presented for naphthalene oriented in stretched polyethylene and polypropylene matrices at 77 K and 296 K. From the calculated spectrum LD(λ)/ A (λ), where A (λ) is the corrected absorbance spectrum of the sample by unpolarized light, orientational parameters are calculated and component spectra, 235–315 nm, are resolved corresponding to polarization parallel to the long (B 3u = x ) and the short (B 2u = y ) axes in the molecular plane (D 2h ). The orientational parameters indicate different orientational mechanisms in polyethylene and polypropylene, but the resolving procedure yields mainly identical component spectra. It is suggested that the polarization (B 3u ) predominating in the 245–275 nm region isdue to a B 1g vibronic perturbation of the 1 B 2u state.

A method is described for determining the refractive index of, e.g., a liquid solution, within an absorption band by studying the linear dichroism generated by different reflections at inclined optical incidence. The method requires a sensitive differential photometric technique, such as that accomplished in a circular dichroism spectrometer. The refractive index of CS2 is reported in the region 260–450 mm. and the result compared to that obtained from a Kramers-Kronig integration on the 320 nm absorption band. Though this band is fairly isolated the experimentally gained result was found more reliable. This was due to difficulties in obtaining an accurate absorption coefficient of liquid CS2 as well as to the fact that the integration had to be restricted to a finite spectral range.

A semi-empirical SCF-MO method, the PEEL method, has been applied in an investigation of the electronic structure and excited states of two iron compounds, [Fe(II)-(GMI)3]++ and [Fe(II)-(bipy)3]++. The electronic absorption spectra have been recorded. The calculations show that it is necessary to account for the trigonal distortion and the covalency in order to explain these spectra quantitatively. Mossbauer measurements have also been performed. The calculated electronic population of the iron is in accord with Mossbauer isomer shift data, indicating that a realistic electron distribution has been obtained by the PEEL method.

Optically active 1,2-dithiane has been produced in a hydrocarbon g ass at 77 K by photolysis with circularly polarised light. Its CD spectrum (above 270 nm) consists of a single symmetric component coinciding with the position of the low energy absorption band. The possibility of using the method to study any per se chiral but at room temperature statistically optically inactive molecule is stressed. A relation yielding Δϵ is presented.

Studies of linear dichroism, using a differential technique, on pyridine and pyrazine, quasi-oriented in stretched polymer matrices, give evidence for the energy positions of the n-π * transitions. These molecules are mainly oriented in the same way as benzene, i.e., the orientation axes in the molecular plane are almost degenerate, and the out-of-plane polarized transitions appear as negative linear dichroism components.

WE report here the first successful optical resolution experiments using low temperature chromatography, for which we used the tris-acetylacetonato (acac) complexes of Al(III) and Fe(III). Since the apparently unsuccessful attempts to resolve Fe(oxalate)3− at −30 °C on starch1, only room temperature experiments have been reported (for example, refs 2–4).

A new transition recently suggested at 265 nm in dialkyl anilines is confirmed by linear dichroism in an oriented matrix.