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) )
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. |