• B V Raghavendra Rao

      Articles written in Proceedings – Section A

    • Some multiplets in the Ag III spectrum

      B V Raghavendra Rao

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      By a consideration of the isoelectronic sequence Rh I, Pd II and Ag III, the terms 4d8(3F)5s4F &2F and 4d8(3F)5p4F′ &2F′ of Ag III have been identified. The Moseley diagram for the corresponding terms of the members of the sequence is also given in the paper. The absolute value of the term 4d8(3F)5s4F9/2 comes out as equal to 237000·0 cm−1 corresponding to an ionisation potential of about 29·25 volts.

    • Examination of molecularly scattered light with a Fabry-Perot etalon - Part I. Liquid benzene

      B V Raghavendra Rao

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      The fine structure of the Rayleigh line due to molecular scattering in liquids has been investigated with a Fabry-Perot interferometer and the two fine structure components identified for the first time with this instrument. The agreement between the observed and calculated values of the displacements of these new fine structure components is particularly good, in the case of the liquid used (Benzene). The dependence of the frequency shift of the displaced components from the central main line on the frequency of the incident radiation has also been verified in complete agreement with Brillouin’s equation. Photographic reproductions of the interference patterns obtained with the three lines of Hg,i.e., λ 4358 Å, λ 4078 Å and λ 4047 Å have been included in the paper from which one can clearly identify the two fine structure components due to molecular scattering as is to be expected from Brillouin’s theory. It is found that the central undisplaced component is distinctly brighter than the two side components due to scattering.

    • Examination of molecularly scattered light with a Fabry-Perot Etalon - Part II. Liquids: Toluene and carbon tetrachloride

      B V Raghavendra Rao

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      In continuation of the author’s previous work on benzene, the study of the fine structure of the Rayleigh line has been extended to the cases of carbon tetrachloride and toluene with improved experimental technique. Very clear photographs of the interference pattern free from continuous background have been obtained with carbon tetrachloride and it has been found that the relative intensities of the central and the outer Doppler components is much greater in the case of carbon tetrachloride than in toluene. This fact leads us to the conclusion that, though the anisotropy of the molecules does contribute towards the central line (Q branch), it is not in main responsible for the appearance of the central undisplaced component. It is only the wings on either side of theRayleigh line, which become more and more prominent with increase of anisotropy of the molecules constituting the scattering medium. On account of the high scattering power of toluene, it was possible to extend the observation and test the Doppler shifts of λ 5461 Å, in agreement with equation (1). The experimental data obtained in the investigation have been examined and some relevant theoretical aspects of the problem are discussed in the last section of the paper.

      The question of thereality of the red shift of the centre of the Rayleigh line observed by Cabannes has been investigated and it has been shown that there is no shift of such a nature. The conditions under which a spurious red shift might be observed have been examined and it is found that temperature and pressure variations of the surrounding atmosphere affect the interference pattern of the scattered light when exposures are of very long duration.

    • The doppler effect in light scattered by liquds - Part I. Variation with temperature

      B V Raghavendra Rao

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      The influence of temperature on the nature of the Doppler effect in light scattered by liquids has been examined and it is found that in the case of carbon tetrachloride at 70°C. the Doppler components become fainter and broader merging with the central undisplaced component which brightens up in intensity. At the temperature of melting ice, the Doppler components become sharper and move away from the central component.

    • Dippler effect in light scattering in liquids - Part II. Polarisation of the transversely scattered radiations

      B V Raghavendra Rao

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      The present paper describes a study of the state of polarisation of the three components observed in the spectrum of the scattered light when examined with a Fabry-Perot etalon. Three typical liquids, carbon tetrachloride, toluene and carbon disulphide have been examined. The results indicate that the two Doppler components are completely polarised as is to be expected, and that the central component is practically completely polarised. The significance of the latter result which appears surprising at first sight, is discussed in some detail.

    • Doppler effect in light scattering in liquids - Part III. polarisation of light transversely scattered by formic and acetic acids

      B V Raghavendra Rao

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      The present work deals with the study of the state of polarisation of the three components observed in the spectrum of monochromatic light scattered by liquid formic and acetic acids, when examined with a Fabry-Perot etalon. It is noticed with these liquids that the central undisplaced component of the triplet observed on analysing the transversely scattered light spectrographically with a Fabry-Perot etalon shows an appreciable degree of depolarisation, differing in this respect from non-associated liquids like carbon tetrachloride, toluene and carbon disulphide, in which the central component is unobservable in the horizontal vibration of the transversely scattered light. There is thus an indication of the presence of large non-rotating or immobile clusters of molecules in these liquids which depolarise the scattered light.

    • Dispersion of acoustic velocity in liquids

      B V Raghavendra Rao

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