Fig. 8: Water lines recorded by heterodyne spectroscopy.
From: Frequency stable and low phase noise THz synthesis for precision spectroscopy
Examples of recorded water lines (black points) around 557, 988, and 1410 GHz were corrected from the 83 kHz frequency shift due to AOM modulators. Fitted positions (orange lines), using a Voigt profile on a third-order polynomial baseline, are compared to the HITRAN database (red sticks). Non-flat residuals (green lines) may suggest the presence of saturation effects (see text).
