Knowledge Bank

The $CH2F$ radical is an intermediate in the decomposition of various atmospheric species and is also important in free radical addition reactions. Previous work on the $CH2F$ radical has utilized microwave spectroscopy to determine rotational transitions within the ground vibrational state (the symmetric C-H $stretch)a$. Infrared spectroscopic methods have also been used to probe the v3 band (C-F stretch) origin and rotational $constantsb$. We have used high resolution $(0.0005cm-1)$ infrared spectroscopy to investigate rovibrational transitions and assign band origins for both the symmetric and asymmetric stretch region of the $CH2F$ radical. Measurements were taken using direct absorption ($sensitivity=1\times 10-7$ per root Hz) under slit-jet cooled conditions (20 K). Assignment of the spectrum (up to J=7) has yielded refined lower and upper state rotational and centrifugal distortion constants for this near-prolate top. The ratio of absorption intensities for the symmetric and asymmetric bands provides an interesting comparison to that of the $CH2Cl$ radical, where no asymmetric band was detected. Interpretation of hyperfine structure will also be discussed.