  The presence of soft x-rays is very important for the chemical evolution of
interstellar medium and other astrophysical environments close to young and
bright stars. Soft X-rays can penetrate deep in molecular clouds and
protostellar disks and trigger chemistry in regions in which UV stellar photons
do not reach. The effects of soft X-rays in astrophysical ices are also
remarkable because they release secondary electrons in and on the surface of
the ices, which trigger a new set or chemical reactions. In this chapter we
will discuss firstly about the origin and relevance of soft X-rays in
astrophysics. Next we will move to the effect of ionizing radiation in organic
molecules present in astrophysical environment. We will discuss the use soft
X-rays in astrochemistry laboratory studies at both gas- and solid-phase (ice).
We will make a review covering our publications in this field, in particular,
about the experiments employing time-of-flight spectroscopy (TOF-MS), Fourier
transform infrared (FTIR) spectroscopy and photon stimulated ion desorption
(PSID-TOF-MS). This study help us to understand the chemical evolution several
astrophysical regions and also put constrains in the researches related with
the life's origin.
