The characterization of aircraft particulate matter (PM) emissions has benefited greatly by the Aerosol Mass Spectrometer (AMS) by providing size resolved compositional information. AMS data have been critical to much of our understanding of aircraft PM emissions, but it has limited utility in probing the smallest (<100 nm) particles in the exhaust. Also, to date the AMS has been able to detect only volatile PM and other instruments have been required to characterize the non-volatile (soot). We propose to improve greatly the capabilities of a novel version of the AMS to cover two important gaps in our understanding of gas turbine engine particle emissions: 1) size resolved composition of particles with diameters less than 50 nm; 2) size resolved mass and chemical composition (e.g., fullerenic composition) of black carbon soot. Specifically in Phase I, we aim to: 1) improve AMS detection of particles smaller than 100 nm by refining an existing computational fluid dynamics (CFD) model and use the CFD model to guide the design of new AMS particle focusing designs, and 2) evaluate for model soot characterization a newly developed instrument which combines a laser ablation system with AMS technology -- an instrument which we have termed the SP2-AMS.