We propose to use the LWS to obtain the complete FIR spectra
 of gas surrounding seven OB stars in the NGC 6334 complex.  Our
 goal is to examine in detail the impact of the ultravliolet field
 strengths on its photodissociation regions (PDRs), the interfaces
 between the H II regions and the ambient molecular medium.  NGC 6334
 provides a unique stellar laboratory to study PDRs because (1) it has
 at least seven well-separated OB stars, (2) the stellar spectral
 types encompass an enormous range in ultraviolet field strengths,
 (3) the stars all lie at the same distance within the same molecular
 cloud, and (4) the region is relatively nearby.  The unsurpassed
 sensitivity of ISO will allow us to detect a number of FIR lines.
 The atomic fine structure lines are PDR diagnostics.  The ionic lines
 provide a measure of the hardness of the UV field, H II region
 densities, and element abundances.  The molecular lines of H2O, CO,
 OH, and NH3 probe the warm, dense molecular gas associated with the
 PDRs.  These observations will allow for the first time a direct
 comparison of PDRs from single stars of known UV field strengths.
 We will compare our new FIR data with our molecular line, radio
 and FIR continuum data to obtain a complete census of the ISM in all
 of its phases to determine empirically the effect of UV field
 strength on the surrounding ambient gas and to test the predictions
 theoretical PDR models.