The high precision X-ray spectroscopy studies of plasma created
from the CO2 clusters in gas jet targets by the
ultrashort laser pulses (35 and 60 fs duration) were performed
at the intensities IL ∼
1017–1018 W cm−2. The
spectral line shape of the H-like and He-like oxygen ions gains
an asymmetry with increasing the laser pulse intensity. Theoretical
modeling of the line shape shows that the asymmetry can be
explained by absorption of the Doppler-shifted line radiation
from the essential fraction of ions (over 10−3)
with energies above 1 MeV due to photoionization of inner shells
of carbon ions. The results obtained demonstrate measurement
capabilities of the X-ray spectral measurements of multicharged
ions accelerated during the interaction with a laser radiation.