Investigating the Molecular Complexity of the Interstellar Medium Público
Kroll, Jay Arthur (2012)
Published
Abstract
Abstract
Investigating the Molecular Complexity of the Interstellar
Medium
A new supersonic expansion source has been developed to produce
unstable molecules of
astrochemical interest through O(1D) insertion
reactions. This source has been designed to
allow for the production of O(1D) through photolysis of
Ozone (O3) without photolyzing the
precursor organic molecules. In addition the rotational spectrum of
methyl ethyl ketone (MEK)
has been acquired from 8GHz to 1THz. The spectrum has been analyzed
using three spectral
fitting programs - the CALPGM suite of programs, XIAM, and ERHAM.
The current prediction
had been obtained using ERHAM and fits the 2904 assigned
transitions reasonably well. This fit,
however, fails to match several previously assigned E state
transitions in the cm-wave region
that arise due to splitting from the internal motion of the methyl
group. It also fails to
extrapolate and match the laboratory well beyond ~500 GHz. It is
believed the fit has converged
to a non-physical local minimum and requires further refinement in
order to accurate fit the
entire ground state. Observational spectra of 6 interstellar
sources have been collected using
the Caltech Submillimeter Observatory (CSO). These spectra were
examined for evidence of
coincidental transitions with the strongest assigned MEK lines.
None were observed. However,
due to the incomplete nature of the fit for MEK it should not be
ruled out as a potential
interstellar molecule.
Table of Contents
Table of Contents
1 -
Introduction………………………………………………………………………………………………………………………..1
2 - O(1D)
Reactions…………………………………………………………………………………………………………………..2
3 - Source
Design……….…………………………………………………………………………………………………………….6
4 - Methyl Ethyl Ketone
………………………………………………………………………………………………………….10
5 - MEK Spectral
Acquisition……………………………………………………………………………………………………12
6 - MEK
Hamiltonian…………….…………………………………………………………………………………………………15
7 - MEK Results and
Analysis…………………………………….…………………………………………………………….24
8 - Astronomical Observations
……………………………………………………………………………………………….34
9
-Conclusion…………………………………………………………………………………………………………………………..40
Sources
Cited…………………………………………………………………………………………………………………………..42
Appendix
A………………………………………………………………………………………………………………………………45
Figures
1 - Unstable molecules through O(1D)
Insertion…………………………………………………………………….…4
2 - Fast Mixing Photolysis Supersonic Expansion Source
Design…………………………………………….…6
3 - First Fast Mixing Photolysis Supersonic Expansion
Source…………………………………………………...7
4 - Second Fast Mixing Photolysis Supersonic Expansion
Source…………………………………………….…7
5 - New Expansion Source for Ozone
Use……………………………………………………………………………..….9
6 - Interstellar Molecules Similar to Methyl Ethyl
Keton………………………………………………………….10
7 - CP-FTMW Spectrometer
Diagram………………………………………………………………………………………12
8 - VDI Multiplier Chain Setup and Band
Coverage………………………………………………………………….14
9 - Direct Absorption Flow Cell
Diagram………………………………………………………………………………….15
10 - V3 Barrier to Internal Rotation of a Methyl
Group…………………………………………………………...20
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