New laboratory techniques using heterodyne receivers

TL;DR

This paper presents a detailed calibration and feasibility study of a new submillimeter spectrometer, SURFER, operating between 300-400 GHz, and explores extending detection capabilities up to 2 THz for astrophysical applications.

Contribution

It introduces a new laboratory spectrometer SURFER with calibration details and assesses the potential to detect molecular transitions up to 2 THz.

Findings

Successful calibration of SURFER spectrometer.

First rotational spectra of vinyl cyanide at 2 THz obtained.

Feasibility demonstrated for astrophysical molecule detection at higher frequencies.

Abstract

Two laboratory emission spectrometers have been designed and described previously. Here, we present a follow-up study with special focus on absolute intensity calibration of the new SURFER-spectrometer (SUbmillimeter Receiver For Emission spectroscopy of Rotational transitions), operational between 300 and 400~GHz and mostly coincident with ALMA (Atacama Large Millimeter/submillimeter Array) Band 7. Furthermore, we present a feasibility study to extend the detection frequencies up to 2~THz. First results have been obtained using the SOFIA (Stratospheric Observatory for IR Astronomy) upGREAT laboratory setup at the University of Cologne. Pure rotational spectra of the complex molecule vinyl cyanide have been obtained and are used to give an estimate on the sensitivity to record ro-vibrational transitions of molecules with astrophysical importance at 2~THz.