A new design for a simple and effective pyrolysis nozzle in a supersonic free jet

A new design for a pyrolysis nozzle to be used in conjunction with a supersonic free jet is presented. Advantages include its simple construction and inexpensive materials. The difluorocarbene (CF2) radical was chosen as a test molecule, and its Ã(1 B 1)←X̃(1 A 1) electronic transition was examined using laser induced fluorescence spectroscopy. The radical was formed by pyrolysis of C2F4 at ∼1200 K within the nozzle. The effect of different nozzle designs on the subsequent vibrational and rotational cooling was investigated. Small changes in design and expansion conditions resulted in large changes in ultimate rotational and vibrational temperature.