Chemical complexity of phosphorous bearing species in various regions of
  the Interstellar medium
  Phosphorus related species are not known to be as omnipresent in space as
hydrogen, carbon, nitrogen, oxygen, and sulfur-bearing species. Astronomers
spotted very few P-bearing molecules in the interstellar medium and
circumstellar envelopes. Limited discovery of the P-bearing species imposes
severe constraints in modeling the P-chemistry. In this paper, we carry out
extensive chemical models to follow the fate of P-bearing species in diffuse
clouds, photon-dominated or photodissociation regions (PDRs), and hot
cores/corinos. We notice a curious correlation between the abundances of PO and
PN and atomic nitrogen. Since N atoms are comparatively abundant in diffuse
clouds and PDRs than in the hot core/corino region, PO/PN reflects < 1 in
diffuse clouds, << 1 in PDRs, and > 1 in the late warm-up evolutionary phase of
the hot core/corino regions. During the end of the post-warm-up phase, we
obtain PO/PN > 1 for hot core and < 1 for its low mass analog. We employ a
radiative transfer model to investigate the transitions of some of the
P-bearing species in diffuse cloud and hot core regions and estimate the line
profiles. Our study estimates the required integration time to observe these
transitions with ground-based and space-based telescopes. We also carry out
quantum chemical computation of the infrared features of PH3 along with various
impurities. We notice that SO2 overlaps with the PH3 bending-scissoring modes
around ~ (1000 - 1100) cm-1. We also find that the presence of CO2 can strongly
influence the intensity of the stretching modes around ~ 2400 cm-1 of PH3 .
