The high energy particles (electrons and protons) passing through the
lower atmosphere of Venus are attenuated and produce ionization of atm
ospheric constituents. In this paper, the loss of energy of electrons
(10(5) < E < 10(8) eV), protons (10(7) < E <10(12) eV), and Bremsstrah
lung radiation due to electrons of energy 10(4) < E < 10(8) eV have be
en computed. The results are used to study the impact and Bremsstrahlu
ng photoionization in lower ionosphere of Venus. The production rate d
ue to the attenuation of energetic particles has been evaluated. It is
shown that the production rate due to non-relativistic protons is dom
inating above 100 km, whereas below this height extreme relativistic p
rotons are effective and produce a peak at the height of 65 km.