Knowledge Bank

The structural parameters of the chloroform molecule have been $determined1$ precisely enough to predict the microwave spectrum of the asymmetric isotopic species $CDCl2\mathrm{<mrow\; data-mjx-texclass="ORD">25</mrow>}Cl37$. However, a careful search with two different microwave spectrographs for some of the predicted lines for this species has failed to reveal lines at the predicted frequencies and instead has resulted in the measurement of some spectrum lines whose frequencies differ by as much as 10 Mc/s from the predicted values. In addition, a strong multiplet has been measured at 25,345 Mc/s in pure $CDCl3$ at dry ice temperature and this line has not as yet been identified.