Near-Infrared Spectroscopy of Photodissociation Regions: The Orion Bar   and Orion S
  To test the PDR model spectra under the physical conditions present in Orion, we have obtained moderate-resolution (R=3000) J-, H-, and K-band long-slit spectra of the Orion bar and Orion S regions These observations provide conclusive evidence for the PDR origin (rather than shocks) of the H_2 emission in each of these regions and demonstrate significant departures in the observed chemical structure from that predicted by models of homogeneous PDRs. 
K. L. Luhman, C. W. Engelbracht, M. L. Luhman