GaAs1-xNx films have been grown using chemical beam epitaxy (CBE). Triethylgallium, As-2 and atomic nitrogen generated in an electron cyclotron resonance plasma were used as the Ga, As and N sources, respectively. The maximum nitrogen content in GaAs1-xNx obtained in this study was x = 0.026. As a supplemental method to secondary ion mass spectrometry and X-ray diffraction techniques for measuring the nitrogen fraction, we present preliminary results from transmission electron microscopy studies which involved the use of microdiffraction and electron energy loss spectroscopy to probe local regions of the films.