Infrared radio-frequency double resonance and Zeeman spectroscopy of thioformaldehyde

Two new double resonance signals were observed in H 2 CS using the 10R4 CO 2 laser line. Both radio-frequency transitions have been assigned. Their behavior in a magnetic field up to 10.5 kG has been studied. One signal was pumped by the 9P20 laser line and the other two by the 10R4 laser line. A 10R4 signal observed at 15.8 MHz was assigned to the 11 3.8 yields 11 3.9 transition in the v 6 ground state of H 2 CS. The other 10R4 signal, which was observed at 202.8 MHz, was assigned to the 11 2.9 yields 11 2.10 transition in the excited state. This transition is the first to be reported in an excited vibrational state of the electronic ground state. The frequency of this transition was found to be strongly influenced by Coriolis coupling between the v 4 and v 6 states.