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Universität zu Köln
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Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Methods

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Emission Spectroscopy

Description

Traditionally the vast majority of lab spectroscopy measurements have been absorption measurements, where a strong tunable source can provide a high signal-to-noise ratio. With today's high sensitivity of state-of-the-art astronomical heterodyne receivers and their ever growing instantaneous bandwidth, emission spectroscopy becomes a more and more interesting alternative, which will ultimately outperform absorption spectroscopy in terms of scanning speed at a not comparable, but desired signal-to-noise ratio. In 2014 the emission spectroscopy method has been employed in our laboratory for the first time for measurements of rotational spectra of complex molecules of astrophysical demand at 800 GHz. In 2016 we employed a 100 GHz room-temperature emission spectrometer for the first time (accepted IAU proceedings 2017). In 2017 we obtained first results using an emission spectrometer coupled to a highly sensitive SIS-mixer operational between 300 and 400 GHz, coincident with ALMA Band 7. ...more

Figure(s)

TErahertz Laboratory eMIssion spectrometer (TELMI) operational at 800 GHz
SURFER Emission Spectrometer operational between 300 and 400 GHz
100 GHz room-temperature receiver

Instruments

100 GHz room-temperature emission spectrometer
The modern developments of highly sensitive room-temperature low-noise amplifiers in combination with room-temperature mixers as well as advances in digital Fast Fourier transform spectrometers (FFTSs) for the space and ground observatories make also laboratory emission spectroscopy very attractive, in the light of the possibility of fast measurements of high resolution broadband spectra with high sensitivity and precise line intensities. Thus, emission spectroscopy is of interest for the spectroscopy itself, allowing fast broadband spectral measurements, and for the physical chemistry, providing measurements of absolute line intensities and shapes.
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