A detailed Raman scattering analysis of nitrogen incorporated polycrystalline diamond thin films grown using NH3/CH4/H-2 gas mixture in hot filament chemical vapor deposition system is presented. To understand the nitrogen bonding configuration in these films, diamond films are grown by replacing H-2 with D-2 in the gas mixture. The Raman peak observed at similar to 1190 cm(-1) showed an isotopic shift to similar to 830 cm(-1) upon replacing H-2 with D-2 in the gas mixture. With the present Raman analysis, the peak at similar to 1190 cm(-1) is assigned to C=N-H. Secondary ion mass spectroscopy revealed the abundance of nitrogen in the sub-surface region of the annealed diamond thin films.