Energy loss of subionizing charged particles in polar media

Abstract

After the well‐known paper of Froehlich and Platzman [1] the problem of energy loss of subionizing particles (which does not excite electron transitions in molecules) in dielectrics has been discussed many times in radiation‐chemical literature.Nevertheless the available formulas for dielectric loss rate −dW/dt are distinguished in some cases even parametrically. It is enough for example to compare eqs. (35,43) from [2] in the limit ε∞/ε0⋅ vτ/a ≪ 1 and eq. (23) in [3], which describe dielectric energy loss of a charged particle of radius a moving with the velocity v in a polar media. Here ε0 and ε∞ are the static and high frequency dielectric constants and τ is the relaxation time.The aim of the present paper is to recalculate analytically a dielectric energy loss rate of the particle moving straightforwardly or diffusively in polar media in the frame of excluded sphere approximation. The obtained formula reproduce as the limiting cases the known particular results [1,3]. We have also presented a semiphenomenological approximation for taking into account molecular vibrations. It is shown in accordance with [4] that the energy losses of subionizing electrons in dielectrics are caused mainly by excitations of intra‐ and intermolecular vibrations. The contribution of the temperature dependent Debye losses is small.