Knowledge Bank

An infrared-microwave two-photon spectrometer operating under computer control with $CO2$ or $N2O$ lasers with microwave radiation in the 8-18 GHz region has been used to record 54 transition in the $\upsilon 2$ vibration-rotation band of $\mathrm{<mrow\; data-mjx-texclass="ORD">15</mrow>}NH3$ and 14 transitions in the $\upsilon 3$ band of $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CH3F$. The frequencies of these transitions have been obtained by numerical fitting of the lineshapes. The overall accuracy of frequency measurement is estimated to be $\pm 0.0002cm-1$, with the main contribution to the uncertainty coming from the uncertainty in the laser frequency. The two-photon frequencies for $\mathrm{<mrow\; data-mjx-texclass="ORD">15</mrow>}NH3$ have been combined with previous two-photon $frequencies,1,2$ diode laser $measurements,3$ and microwave inversion $frequencies4$ to obtain vibration-rotation constants for the states involved. The two-photon frequencies for $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}CH3F$ have been combined with previous two-photon $frequencies,5$ laser-Stark $measurements,5$ and ground state rotational constants from microwave $spectroscopy6$ to obtain vibration-rotation constants for the upper state.