Knowledge Bank

Glycolaldehyde is the simplest $\alpha$-hydroxy aldehyde and the only sugar-related molecule definitively detected in the interstellar medium to date. Previous spectral studies, 5, 205-213 (1970).}$,$, 158, 188-192 (2005).} have reported its rotational spectrum up to $\sim$350 GHz. With the advent of several new submillimeter and THz astronomy facilities equipped with high-resolution spectrometers, it is important to begin collecting and analyzing higher frequency spectra for all known interstellar molecules. We have acquired the submillimeter/THz direct absorption spectrum of glycolaldehyde from 520 -- 600 GHz and from 1.1 -- 1.2 THz. The spectra were measured at JPL using a 3-meter static cell in double-pass configuration. The submillimeter radiation was generated using a standard microwave frequency synthesizer coupled with cascaded frequency multipliers. A Schottky diode detector was used during acquisition of the lower frequency spectra, and an Si hot electron bolometer detector was used for scans above 1 THz. The analysis of these spectra is underway, and new line assignments are being combined with the assignments from previous studies to determine a global spectral fit. The details of the experiment and progress on the spectral analysis will be reported.