Skip to Main content Skip to Navigation
Theses

Microwave spectroscopy of glycine and other related molecules. Rotationnal analysis and radioastronomical observations of the interstellar medium.

Abstract : The purpose of this research is to observe the chemical composition of galactic molecular clouds with the goal to gain informations on the origin of Life. The most substantial project concerns the amino acid glycine. The rotational analysis of this prebiotic molecule is conducted in Monash University, Australia. Spectra are difficult to assign. At the temperature of the experiment, 200°C, the population is distributed over a large number of vibrational and rotational levels belonging to several conformers of this ten atoms molecule and to its decomposition products. Also, the microwave spectrometer based on Stark modulation of the absorption lines is not appropriate. Despite difficulties, the identification of lines observed between 26 GHz and 63 GHz could lead to the determination of the rotational parameters and to the components of the dipole moment. The determination of the hyperfin structure, linked to the electrical quadrupole of the nitrogen nucleus, allows to conclude that the studied conformer hosts an hydrogen intramolecular bond. Results are in good agreement with those published later by other laboratories. Radioastronomical observations are performed at Parkes/Australia, Kitt-Peak/Arizona and Onsala/Sweden, in the direction of Orion A and Sagittarius B2 and also 7 other clouds. Six transitions between 22.7 and 83.4 GHz are searched. An upper limit for the column density of glycine molecules along the line of sight is calculated to be 10¹² cm⁻² up to 10¹⁴ cm⁻². Glycine might be less abundant than ethanol and ethyl cyanide. New transitions of methanol and methyl cyanide are detected and equations of radiative transfer and statistical equilibrium are written for an asymmetric top molecule.
Complete list of metadatas

https://tel.archives-ouvertes.fr/tel-01687449
Contributor : Marie-Paule Bassez <>
Submitted on : Thursday, January 18, 2018 - 2:57:56 PM
Last modification on : Wednesday, January 24, 2018 - 1:02:06 AM

File

Bassez1981_Thesis.pdf
Files produced by the author(s)

Identifiers

  • HAL Id : tel-01687449, version 1

Collections

Citation

Marie-Paule Bassez. Microwave spectroscopy of glycine and other related molecules. Rotationnal analysis and radioastronomical observations of the interstellar medium. . Theoretical and/or physical chemistry. Université de Paris-Sud, Centre d'Orsay, 1981. English. ⟨tel-01687449⟩

Share

Metrics

Record views

85

Files downloads

54