Photochemistry (a term that broadly speaking includes photophysics) is
a branch ofmodern science that deals with the interaction of light with matter
and lies at the crossroads of chemistry, physics, and biology. However, before
being a branch of modern science, photochemistry was (and still is today),
an extremely important natural phenomenon. When God said: “Let there be
light”, photochemistry began to operate, helping God to create the world as
we now know it. It is likely that photochemistry was the spark for the origin of
life on Earth and played a fundamental role in the evolution of life. Through
the photosynthetic process that takes place in green plants, photochemistry
is responsible for the maintenance of all living organisms. In the geological
past photochemistry caused the accumulation of the deposits of coal, oil, and
natural gas that we now use as fuels. Photochemistry is involved in the control
of ozone in the stratosphere and in a great number of environmental processes
that occur in the atmosphere, in the sea, and on the soil. Photochemistry is the
essence of the process of vision and causes a variety of behavioral responses in
living organisms.