Sadhan Basu

Charge Transfer and Fluorescence Quenching

A charge‐transfer‐interaction mechanism has been proposed for the quenching of fluorescence of a number of polynuclear aromatic hydrocarbons by aromatic solvents, especially methylated benzenes. The quenching efficiency has been found to be in the order benzene<toluene<xylene<mesitylene, which is also the order in which ionization energy of the solvents diminishes.

Free electron model and photoionization of π-electrons from aromatic hydrocarbons

Using the free electron wave function it has been shown that the propability of photoionization of a π-electron from aromatic hydrocarbons should be maximum if the incident photon has energy sufficient to ionize and to leave an additional momentum p=√5 Kħ2/2 to the escaping electron. This momentum further appears to be independent of the ring size.ZusammenfassungMit Hilfe der Wellenfunktionen des Modells freier Elektronen wird gezeigt, daß die Wahrscheinlichkeit für die Photoionisation eines π-Elektrons aus einem aromatischen Kohlenwasserstoff maximal sein sollte, wenn das auftreffende Photon eine Energie mitbringt, die ausreicht, um die Ionisation herbeizuführen und auf das Elektron ein zusätzliches Moment p=√5 Kħ2/2 zu übertragen. Dieses Moment scheint unabhängig von der Ringgröße des aromatischen Systems zu sein.RésuméEmployant la fonction donde de lélectron libre, on montre que la probabilité de photoionisation dun électron π des hydrocarbures aromatiques devrait être maximale si le photon incident a lénergie pour rendre un électron libre à p=√5 Kħ2/2 de moment. Ce moment ne semble pas dépendre du périmètre du système cyclique.

Free‐Electron Model and Doublet Splitting in Aromatic Hydrocarbon Ions

Doublet splitting in hydrocarbon ions due to spin—orbit interaction arising from electron circulation around the ring has been calculated using a free electron model.

Free electron model and magnetic susceptibility of aromatic hydrocarbons

Using a free electron model for the π-electron system in aromatic hydrocarbons the π- electron susceptibility due to Langevin diamagnetism and Van Vleck High frequency para-magnetism (H. F.) have been calculated. The H. F. term has been found to increase rapidly with the ring size.ZusammenfassungMit Hilfe eines Modells freier Elektronen für das π-Elektronensystem in aromatischen Kohlenwasserstoffen wird der Langevinsche diamagnetische Anteil und der Van Vlecksche paramagnetische Beitrag zur π-Elektronensuszeptibilität berechnet. Dabei findet man, daß letzterer mit der Ringgröße schnell wächst.RésuméAu cadre du modèle de lélectron libre, la susceptibilité π-électronique des hydrocarbures benzéniques due au diamagnétisme de Langevin et au paramagnétisme de Van Vleck (H. F.) a été calculée. Le terme H. F. sagrandit rapidement avec les dimensions de la molécule.

Studies on mechanochemical systems. Part I

A film of partially hydrolyzed (about 33 %) polymethyl acrylate (of av. D.P. 16,310) has been found to undergo reversible mechanochemical expansion-contraction with the extent of neutralization and in salt solutions. An amount of work equivalent to 5268 ergs has been performed using the contractile mechanism isothermally. Donnan osmotic contribution to the swelling of the gel has been found to be negligible in the present case.

Electron transfer spectra in copper ammines

Abstract The absorption spectra of ammine, ethlelnediammine and methylammine complexes of copper as well as of copper glycinate in aqueous solution showed intense absorption bands in the region of 200–250 mμ. These bands have been associated with the electron transfer spectra between the copper and the ammine group. No unequivocal assignment of the direction of electron transfer could be made.

Uv-spectra of the copper chelate of quinoline-8-car-boxylic acid

A comparative study of the absorption spectra of an alcoholic solution of quinolinc-8-carboxylic acid, with and without NaOH and perchloric acid, and its copper chelates has been made and a probable electronic structure for the metal chelates of quinoline-8-carboxylic acid has been suggested.

Studied on heteronuclear intervalence transfer, Part II : Ferricyanides of trivalent cobalt

Ferricyanides of Co (III) tris phenanthroline and tris bipyridyl have been found to show the intervalence electron transfer effect optically as well as thermally. The ferricyanide of tris ethylene diamine Co (III) however do not show the optical effect at all. It has been suggested that the electron transfer takes from Co (III) to Fe (III) converting Co (III) to Co (IV). The role of ligands in stabilising the Co (IV) stale has been discussed.

Studies on mechano-chemical systems, Part III

The expansion-contraction behaviour of 33% hydrolysed polymethyl acrylate gel has been analysed in terms of DONNAN-osmotic effect. It has been shown that the mechanochemical properties may also be explained by osmotic considerations instead of the electrostatic effect that has been done in the previous communication1. A comparative study has shown that both these effects are operative in the present system and only under certain restraining conditions one effect or the other becomes predominant. n n n nDas Expansions-Kontraktions-Verhalten von 33%ig hydrolysiertem Polymethylacrylat-Gel wurde im Hinblick auf den DONNAN-osmotischen Effekt untersucht. Es wurde gezeigt, das die mechanisch-chemischen Eigenschaften auch durch osmotische Betrachtungen erklart werden konnen statt durch den elektrostatischen Effekt, wie es in der fruheren Mitteilung1 erfolgte. Eine Vergleichsstudie zeigte, das beide Effekte im vorliegenden System wirksam sind und nur unter bestimmten einschrankenden Bedingungen der eine oder andere vorherrscht.