Abstract

The detection of CN, an important intermediate in the nitrogen oxidation chemistry of hydrocarbons, in the B²∑⁺ –X²∑⁺ electronic band by degenerate four-wave mixing is reported. The radical source consisted of a H₂/O₂/N₂/C₂H₂/NO atmospheric-pressure premixed flame. We estimate a detection limit of 3 × 10¹³ CN molecules/cm³ and a rotational temperature of 920 K. A tilted backward pump beam degenerate four-wave mixing geometry is investigated, and results show an order-of-magnitude increase in the signal-to-noise ratio over the conventional counterpropagating pump beam geometry.

© 1995 Optical Society of America

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