Astronomy and Astrophysics Seminars

Spectroscopy of the Heavens

by Dr. Thomas Giesen, (University of Kassel, Institute for Physics, Kassel / Germany)

Tuesday, February 16, 2016 from to (Asia/Kolkata)
at TIFR ( Lecture Theatre (AG 66) )
Description
High-resolution terahertz (THz) spectroscopy is a vivid 

field of current research due to its importance in 

astrophysics and molecular physics. New THz telescope 

facilities like ALMA, Herschel, and SOFIA make use of 

accurate (<1 MHz) laboratory line positions in the 

frequency range up to 2 THz to identify interstellar 

molecules and to derive their astrophysical abundance. 

This talk presents current laboratory activities to provide 

the necessary transition frequencies for molecular 

rotation and ro-vibration in the range from 300 GHz up 

to 3 THz. The continuous development and fabrication 

of monochromatic submillimeter (sub-mm) wave 

radiation sources is a key to recent successes of THz 

spectroscopy in laboratory and space. High-resolution 

spectrometers, based on backward wave oscillators, 

multiplier techniques, and laser side band generation and examples of molecules studied at the 

laboratory will be presented. General features of the instruments such as frequency accuracy and 

sensitivity will be discussed in detail. 

Applications include the study of light hydrides, complex molecules, radicals, and molecular ions. 

These transient species are very important molecules in the astrophysical environment because of 

their chemical activity. However characterization of these molecules in the laboratory, is 

experimentally as well as theoretically demanding. Combination of supersonic jets to THz 

spectroscopy will be discussed as recent developments in our laboratory to meet the challenge.

 

Carbon Clusters Produced in a Supersonic Jet 

Expansion of a Laser Ablation Source.