Millimeter Spectral Line Mapping Observations Toward Four Massive Star
  Forming HII Regions
  We present spectral line mapping observations toward four massive
star-forming regions (Cepheus A, DR21S, S76E and G34.26+0.15), with the IRAM 30
meter telescope at 2 mm and 3 mm bands. Totally 396 spectral lines from 51
molecules, one helium recombination line, ten hydrogen recombination lines, and
16 unidentified lines were detected in these four sources. An emission line of
nitrosyl cyanide (ONCN, 14$_{0,14}$-13$_{0,13}$) was detected in G34.26+0.15,
as first detection in massive star-forming regions. We found that the
$c$-C$_{3}$H$_{2}$ and NH$_{2}$D show enhancement in shocked regions as
suggested by evidences of SiO and/or SO emission. Column density and rotational
temperature of CH$_{3}$CN were estimated with the rotational diagram method for
all four sources. Isotope abundance ratios of $^{12}$C/$^{13}$C were derived
using HC$_{3}$N and its $^{13}$C isotopologue, which were around 40 in all four
massive star-forming regions and slightly lower than the local interstellar
value ($\sim$65). $^{14}$N/$^{15}$N and $^{16}$O/$^{18}$O abundance ratios in
these sources were also derived using double isotopic method, which were
slightly lower than that in local interstellar medium. Except for Cep A,
$^{33}$S/$^{34}$S ratio in the other three targets were derived, which were
similar to that in the local interstellar medium. The column density ratios of
N(DCN)/N(HCN) and N(DCO$^{+}$)/N(HCO$^{+}$) in these sources were more than two
orders of magnitude higher than the elemental [D]/[H] ratio, which is
1.5$\times$10$ ^{-5}$. Our results show the later stage sources, G34.26+0.15 in
particular, present more molecular species than earlier stage ones. Evidence of
shock activity is seen in all stages studied.
