Context :

Aims : The physics of star formation is an important issue of Galactic evolution .
Most stars are formed in high density environments ( n > 10 ^ { 4 } cm ^ { -3 } ) emitting lines of diverse molecular transitions .
In the present part of our survey we search for ammonia emitters in the Aquila rift complex which trace the densest regions of molecular clouds .

Methods : From a CO survey carried out with the Delingha 14-m telescope we selected \sim 150 targets for observations in other molecular lines .
Here we describe the mapping observations in the NH _ { 3 } ( 1,1 ) and ( 2,2 ) inversion lines of the first 49 sources performed with the Effelsberg 100-m telescope .

Results : The NH _ { 3 } ( 1,1 ) and ( 2,2 ) emission lines are detected in 12 and 7 sources , respectively .
Among the newly discovered NH _ { 3 } sources , our sample includes the following well-known clouds : the starless core L694-2 , the Serpens cloud Cluster B , the Serpens dark cloud L572 , the filamentary dark cloud L673 , the isolated protostellar source B335 , and the complex star-forming region Serpens South .
Angular sizes between 40 ^ { \prime \prime } and 80 ^ { \prime \prime } ( \sim 0.04 - 0.08 pc ) are observed for compact starless cores but as large as 9 ^ { \prime } ( \sim 0.5 pc ) for filamentary dark clouds .
The measured kinetic temperatures of the clouds lie between 9 K and 18 K. From NH _ { 3 } excitation temperatures of 3 - 8 K we determine H _ { 2 } densities with typical values of \sim ( 0.4 - 4 ) \times 10 ^ { 4 } cm ^ { -3 } .
The masses of the mapped cores range between \sim 0.05 and \sim 0.5 M _ { \odot } .
The relative ammonia abundance , X = [ NH _ { 3 } ] / [ H _ { 2 } ] , varies from 1 \times 10 ^ { -7 } to 5 \times 10 ^ { -7 } with the mean \langle X \rangle = ( 2.7 \pm 0.6 ) \times 10 ^ { -7 } ( estimated from spatially resolved cores assuming the filling factor \eta = 1 ) .
In two clouds , we observe kinematically split NH _ { 3 } profiles separated by \sim 1 km s ^ { -1 } .
The splitting is most likely due to bipolar molecular outflows for one of which we determine an acceleration of \dot { V } \raise 1.29 pt \hbox { $ < $ \kern - 7.5 pt \raise - 4.73 pt \hbox { $ \sim$ } } 0.03 km s ^ { -1 } yr ^ { -1 } .
A starless core with significant rotational energy is found to have a higher kinetic temperature than the other ones which is probably caused by magnetic energy dissipation .

Conclusions :