Molecular Filtered Electronic Resonance Enhanced NO Raman Scattering

Research Support Instruments and the Applied Physics Group of the MAE Department of Princeton University are partnering to develop a unique laser diagnostic technique based on electronic resonance enhanced Raman scattering. This technique will allow for quantitative measurements of nitric oxide (NO) concentrations in a high temperature, high-pressure environment such as may be found in modern engines currently under development. The diagnostic technique that we propose to develop uses resonantly enhanced incoherent Raman scattering. As a result, the signal is not subject to quenching and is linearly proportional to the density of NO molecules in the resolved volume. Our technique utilizes a unique process whereby the resonant Raman light scattered from either an illuminated planar cross section or line within a test cell is spectrally filtered in a two-stage process that strongly suppresses background light and preserves the image of the probe volume. If successful, this new concept will provide a means whereby the quantitative data can be collected over a wide range of temperature and pressure. This data can then be used to develop pressure scaling laws for NO production