Search for Interstellar Adenine
  It is long debated if pre-biotic molecules are indeed present in the
interstellar medium. Despite substantial works pointing to their existence,
pre-biotic molecules are yet to be discovered with a complete confidence. In
this paper, our main aim is to study the chemical evolution of interstellar
adenine under various circumstances. We prepare a large gas-grain chemical
network by considering various pathways for the formation of adenine. Majumdar
et al. (2012) proposed that in the absence of adenine detection, one could try
to trace two precursors of adenine, namely, HCCN and NH_2CN. Recently Merz et
al. (2014), proposed another route for the formation of adenine in interstellar
condition. They proposed two more precursor molecules. But it was not verified
by any accurate gas-grain chemical model. Neither was it known if the
production rate would be high or low. Our paper fills this important gap. We
include this new pathways to find that the contribution through this pathways
for the formation of Adenine is the most dominant one in the context of
interstellar medium. We propose that observers may look for the two precursors
(C_3NH and HNCNH) in the interstellar media which are equally important for
predicting abundances of adenine. We perform quantum chemical calculations to
find out spectral properties of adenine and its two new precursor molecules in
infrared, ultraviolet and sub-millimeter region. Our present study would be
useful for predicting abundance of adenine.
