We report the first detection of [ \ion C1 ] ( ^ { 3 } P _ { 1 } \rightarrow ^ { 3 } P _ { 0 } ) emission at 609 \mu m in a region of the Small Magellanic Cloud ( N27 ) .
Environments poor in heavy elements and dust such as the SMC are thought to be dominated by photodissociation regions .
This is the lowest metallicity source where submillimeter neutral carbon emission has been detected .
Studying the I _ { [ CI ] } /I _ { CO } ratio in several sources spanning more than an order of magnitude in metallicity , Z , we find that the I _ { [ CI ] } /I _ { CO } ratio increases for decreasing Z .
The existence of such a trend points to a photodissociation origin for most of neutral carbon in molecular clouds , in agreement with standard PDR models .
We also report ISO FIR spectroscopic observations of N27 , and use them to derive its physical properties .
Comparison between the density and radiation field revealed by FIR diagnostics ( n \sim 300 —1000 cm ^ { -3 } , \mbox { $ \chi _ { uv } $ } \sim 30 — 100 \chi _ { 0 } ) and those derived from millimeter and submillimeter data ( n \sim 10 ^ { 5 } cm ^ { -3 } , \mbox { $ \chi _ { uv } $ } \lesssim 30 \chi _ { 0 } ) suggests that the FIR lines originate in more diffuse gas , and are perhaps dominated by the interclump medium .
Regardless of the cause , analysis of the FIR and mm-submm data produces a discrepancy of two orders of magnitude for the density of this source .