Knowledge Bank

Merer and Travis reported that the $ \tilde{A}^{1}A^{\prime\prime}(010)-\tilde{X}^{1}A^{\prime}(000)$ vibronic transition of HCF was remarkably $perturbed.1$ In view of the importance of carbene derivatives in various fields, we investigated this HCF band by cw dye laser spectroscopy with the Doppler-limited resolution. Furthermore, we studied the perturbed lines of the band under the magnetic field up to 2.3 T. HCF was produced by the reaction of microwave discharged $CF4$ with $CH3F$. The subbands of $Ka\prime -Ka\prime \prime =3-4,2-3,1-2,0-1,1-0,2-1,0-0,1-1,2-2,2-0,$ and $0-2$ were assigned using ground state combination differences. Every subband was found to be perturbed to some decree. The perturbations observed in this band were very irregular except the low J transitions with $Ka\prime =1$. The perturbations for the $Ka\prime =1$ levels were well explained by an electronic Coriolis interaction with a highly excited vibrational level in the electronic ground state, The irregularly perturbed lines often showed considerably large magnetic activity. Therefore the origin of some of these perturbations has been believed to be the lowest triplet state.