The possibility of observation of positronic states and phase transitions at the porous silicon surface

The kinetic scheme of transitions and annihilation decays of positronic and positronium states in the volume of a crystal, crystalline skeleton, on a surface, and in the volume of pores of a porous silicon is presented. The formulas linking the intensities of the time components of annihilation decay τij(Iij) with the velocities of decays and transitions of positronic and positronium states in the volume of pores are obtained. The estimation of the interaction constant kx with the surface of pores accompanied by the formation of the surface state of a positronium atom gives kx approx 107 - 108 s-1 and the average value of a pore radius approx 2 nm. The possible explanation of surface phase transitions in porous silicon, observed with the help of positron annihilation spectroscopy, is given