We present new radio-frequency interferometric maps of emission from the ^ { 14 } NH _ { 3 } , ^ { 15 } NH _ { 3 } , and NH _ { 2 } D isotopologues of ammonia , and the ^ { 12 } CH _ { 3 } OH and ^ { 13 } CH _ { 3 } OH isotopologues of methanol toward Sgr B2 ( N ) .
With a resolution of \sim 3 ^ { \prime \prime } ( 0.1 pc ) , we are able to spatially resolve emission from two hot cores in this source and separate it from absorption against the compact H ii regions in this area .
The first ( N1 ) is the well-known v = 64 km s ^ { -1 } core , and the second ( N2 ) is a core 6 ^ { \prime \prime } to the north at v = 73 km s ^ { -1 } .
Using emission from ^ { 15 } NH _ { 3 } and hyperfine satellites of ^ { 14 } NH _ { 3 } metastable transitions we estimate the ^ { 14 } NH _ { 3 } column densities of these sources and compare them to those of NH _ { 2 } D. We find that the ammonia deuteration fraction of N2 is roughly 10-20 times higher than in N1 .
We also measure an [ ^ { 15 } NH _ { 3 } / ^ { 14 } NH _ { 3 } ] abundance ratio that is apparently 2-3 times higher in N2 than N1 , which could indicate a correspondingly higher degree of nitrogen fractionation in N2 .
In addition , we find that N2 has a factor of 7 higher methanol abundance than N1 .
Together , these abundance signatures suggest that N2 is a younger source , for which species characteristic of grain chemistry at low temperatures are currently being actively liberated from ice mantles , and have not yet reached chemical equilibrium in the warm gas phase .
The high D abundance and possible high ^ { 15 } N abundance in NH _ { 3 } found in N2 are interesting for studying the potential interstellar origin of abundances in primitive solar system material .