Rotational polarisability

Figure 14.13—Zeeman effect correction. Instrument showing the principle used for correction of absorbance by the Zeeman effect. Two solutions are applicable I) magnetic field, B, switched alternately on and off and a fixed polariser 2) fixed magnetic field, B, and a rotating polariser.

Fig. 18.5. Comparison of the polarisation modulated (PM-IRRAS) spectra of linear COad, derived from adsorption of CO and of methanol from solution onto a Pt surface from, respectively, CO(sat)/0.5 M H2S04 and 1 M MeOH/O.5 M H2S04 at 0.4 V for 15 min. The polarisation modulation was conducted at 80 Hz by using a rotating polariser, and spectra are referred to 0.8 V. The total adsorbate coverage of 0.86 is common to the two spectra.

One enantiomer rotated polarised li t to the right or clockwise, and it was referred to as (+)-glyceraldehyde. The other rotated polarised light to the left or counterclockwise and was referred to as (-)-glyceraldehyde. The two enantiomers of glyceraldehyde were, according to their Fischer projections called D and L, from the Latin word dexter (right) and laevus (left). 

The fact that an enantiomer can rotate polarised light clockwise (d- or +- enantiomer) does not relate with the relative configuration (D- or L-) of it. 

The second kind of ellipsometer relies upon measuring the intensity changes produced by continuously rotating polarising elements or modulation elements based on cyclic variations of the plane of polarisation or of retardance [Fig. 5(b)], A great many designs have been published, and a comprehensive review of the theory and practice of such designs is available [5],... 

In principle, an anisotropy decay instmment can also be built with a rotating polariser, see Fig. 5.19. 

AAS (a) Transverse magnetic field, i.e. the (b) Instruments in which the longitudinal magnetic field is perpendicular to the optical magnetic field is oriented parallel to the optical axis of the spectrometer. The rotating polariser axis of the spectrometer do not require a po-provides alternately p- and s-polarised radiation lariser. when the magnetic field is constant or trans-... 

One enantiomer rotated polarised ligjhtto the right or clockwise, and it was referred to as (+)-glyceralddiyde. Tte ottier rotated polari light to the or counterclockwise... 

Pasteur was convinced that there must be some molecular difference between the two salts, and he made the problem the subject of his first major piece of research. He prepared several salts of tartaric acid and found that in all cases the crystals were asymmetric (Pasteur used the term dissymmetric), and displayed hemihedral faces. Pasteur was tempted to speculate that such asymmetric crystals were typical of optically active materials, and were the manifestation of asymmetry of the molecules. He then found that crystals of the optically inactive sodium ammonium paratartrate also displayed hemihedral faces, but on careful examination he saw that two types of crystal were present, one the mirror image of the other (Figure 10.13). He carefully sorted some of the crystals by hand. Those with right-handed hemihedry gave a solution which was dextrorotatory and identical with a solution of sodium ammonium tartrate. A solution of equal concentration of the crystals with left-handed hemihedry rotated polarised light to an equal extent in the opposite direction. A solution of equal concentrations of each crystalline form was optically inactive. Pasteur thereby demonstrated that paratartaric acid was... 

Rotational polarisation and translational anisotropy in the recoiling fragments have a profound influence on the intensity distributions in their Doppler resolved LIF excitation (or spontaneous fluorescence) spectra [6] or their multiple photon ionisation spectra [41]. Analysis of the Doppler resolved LIF spectra has provided a powerful method for determining ea( of the three 2-vector correlations as well as their mutual correlation ( p(jjp),kV ) (cf, the triple vector correlations (k, k, ) found in the CS/CH3I full colfision system). 

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