  Prior to the arrival of Cassini-Huygens, aerosol production in Titan's
atmosphere was believed to begin in the stratosphere where chemical processes
are predominantly initiated by FUV radiation. However, measurements taken by
Cassini UVIS and CAPS indicate that haze formation initiates in the
thermosphere where there is a greater flux of EUV photons and energetic
particles available to initiate chemical reactions, including the destruction
of N2. The discovery of previously unpredicted nitrogen species in Titan's
atmosphere by Cassini INMS indicates that nitrogen participates in the
chemistry to a much greater extent than was appreciated before Cassini. The
degree of nitrogen in the haze is important for understanding the diversity of
molecules present in Titan's atmosphere and on its surface. We have conducted a
series of simulation experiments using either spark discharge or FUV photons to
initiate chemistry in CH4/N2 gas mixtures (0.01% CH4/99.99% N2 to 10% CH4/90%
N2). We obtained in situ real-time measurements using an HR-ToF-AMS to measure
the particle composition as a function of particle size and a PIT-MS to measure
the composition of gas phase products. These two techniques allow us to
investigate the effect of energy source and initial CH4 concentration on the
degree of nitrogen incorporation in both the gas and solid phase products. The
results presented here confirm that FUV photons produce not only solid phase
nitrogen bearing products but also gas phase nitrogen species. We find that in
both the gas and solid phase, nitrogen is found in nitriles rather than amines
and both the gas phase and solid phase products are composed primarily of
molecules with a low degree of aromaticity. The UV experiments reproduce the
absolute abundances measured in Titan's stratosphere for a number of gas phase
species including C4H2, C6H6, HCN, CH3CN, HC3N, and C2H5CN. [Edited for length]
