We performed the first spectral-line survey at 82–106 GHz and 335–355 GHz toward the outflow-shocked region , OMC 2-FIR 4 , the outflow driving source , FIR 3 , and the northern outflow lobe , FIR 3N .
We detected 120 lines of 20 molecular species .
The line profiles are found to be classifiable into two types : one is a single Gaussian component with a narrow ( < 3 km s ^ { -1 } ) width and another is two Gaussian components with narrow and wide ( > 3km s ^ { -1 } ) widths .
The narrow components for the most of the lines are detected at all positions , suggesting that they trace the ambient dense gas .
For CO , CS , HCN , and HCO ^ { + } , the wide components are detected at all positions , suggesting the outflow origin .
The wide components of C ^ { 34 } S , SO , SiO , H ^ { 13 } CN , HC ^ { 15 } N , H _ { 2 } ^ { 13 } CO , H _ { 2 } CS , HC _ { 3 } N , and CH _ { 3 } OH are detected only at FIR 4 , suggesting the outflow-shocked gas origin .
The rotation diagram analysis revealed that the narrow components of C _ { 2 } H and H ^ { 13 } CO ^ { + } show low temperatures of 12.5 \pm 1.4 K , while the wide components show high temperatures of 20–70 K. This supports our interpretation that the wide components trace the outflow and/or outflow-shocked gas .
We compared observed molecular abundances relative to H ^ { 13 } CO ^ { + } with those of the outflow-shocked region , L1157 B1 , and the hot corino , IRAS 16293-2422 .
Although we can not exclude a possibility that the chemical enrichment in FIR 4 is caused by the hot core chemistry , the chemical compositions in FIR 4 are more similar to those in L1157 B1 than those in IRAS 16293-2422 .