POSITRONIUM FORMATION IN AQUEOUS-SOLUTIONS OF SURFACTANT SUBSTANCES

Investigating the behaviour of positronium atoms in the solutions of s urface actant (SA) substances Jean and Ache [Jean Y.-C. and Ache H. J. (1978) J. Am. Chem. Soc. 100, 984] have observed a drastic decrease i n the intensity I(ortho) of long-lived ortho-positronium component of Ps atoms when the concentration of SA molecules attains the critical v alue at which the micelle formation begins. This decrease is up to 1/3 from initial I(ortho) value and takes place irrespectively to the sig n of electric charge of arising micelles. The aim of this communicatio n is to give a physical interpretation and quantitative description of the discussed effect based on the model of Ps formation in liquids by combination of positron with one of the quasifree but yet nonsolvated electrons knocked out by positron during its slowing down process, It is shown that the decrease of I(ortho) and positronium formation prob ability P(Ps) is a result of the space segregation of quasifree electr ons (e-) and positron at the end part of its track containing micelles . According to the sign of its electric charge the micelles are able t o accept electrons or positron, making their interaction weaker and th us preventing the Ps formation. The calculations show that the decreas e of P(Ps) (and I(ortho)) may be about several tens of per cent in acc ordance with available experimental data.