High-precision measurement of the temperature of methanol and ethanol droplets using spontaneous Raman scattering

The temperature of liquid methanol and ethanol is demonstrated to be determ ined by a non-intrusive laser technique in sprays. The method is based on s pontaneous Raman scattering, namely the shape and spectral position of the OH stretching band, which is temperature dependent. The accuracy achieved i n this way is about +/-2 degrees C. Thus, it could be applied to precise ev aporation studies in sprays. Furthermore, it is demonstrated that this tech nique can be performed with moderate spectral resolution, although the spec tral shape of a Raman line used for temperature determination. Hence, sever al other vibrational Raman lines can be recorded simultaneously along a lin e by using a spatially resolving optical multichannel analyzer. This yields the possibility to obtain additional spatially resolved information, e.g., air/fuel ratio, vapour/liquid mass fraction, or gas temperature, simultane ously.