Detection Of Deuterated Cyanodiacetylene (Dc5n) In Taurus Molecular Cloud-1

Deuterated cyanodiacetylene (DC/sub 5/N) has been observed for the first time in an interstellar cloud. The J = 10..-->..9 and J = 9..-->..8 transitions have been detected in emission in TMC 1. The abundance ratio DC/sub 5/N/HC/sub 5/N is found to lie in the range 0.006--0.016 overlapping the range 0.013--0.017 observed for DCO/sup +//HCO/sup +/, but somewhat less than the range 0.02--0.08 determined for DC/sub 3/N/HC/sub 3/N. From these observations, it is not possible to rule out the formation of HC/sub 5/N on grain surfaces or by dissociation of larger molecules.