What's that smell? Molecular spectroscopy of nasty gases emitted from volcanoes

(supervisor: Maire Gorman)

Nature of project: data analysis, software

Available to full-time physicists or joint students.

Project description and methodology

The nature of this project is molecular spectroscopy/quantum chemistry: no prior knowledge is needed but a keen interest in learning relevant theory is essential. Please speak to Maire beforehand if you are interested.

A molecular line list is a list of wavelengths and corresponding intensities for a molecule.

The steps required to calculate an accurate and complete line list are detailed below.

For this particular project, students are firstly required to undertake a literature search to identify diatomic molecules of interest in volcanoes.

1. Literature review of existing experimental data and previous theoretical calculations.

2. Collect Dunham and Spectroscopic constants and hence produce a list of energies using a Dunham Expansion/PGOPHER.

3. Use OCR (Optical Character Recognition) software to extract experimental wavelengths from research papers and hence undertake a MARVEL analysis (http://kkrk.chem.elte.hu/marvelonline/) to convert these into a “spectroscopic network” of energies.

4. Compare the list of energies produced by (2) and (3).

5. Calculate Ab initio curves (Potential Energy curves, Dipole moment curves, spin-orbit curves, electronic angular momentum curves) using GAUSSIAN software.

6. Using the list of energies derived, fit analytical Potential energy functions (e.g. Morse).

7. Fit analytical functions to dipole moment, spin-orbit and Electronic-Angular momentum Ab initio curves (step 5).

8. Produce unrefined spectra using only Ab initio calculations (5).

9. Produce refined spectra using fitted functions (6, 7).

A successful project will develop beyond the above in one/some of the following directions:
In order to pass the project, I would expect students to at least successfully undertake steps 1, 2, 6, 8, 9 .

For a student aiming higher I would expect 7 to be undertaken and/or steps 3 & 4.

Undertake step 5.

Extensions to this project would suit students who enjoy coding and wish to learn about numerical fitting methods.

Automate the process of fitting analytical curves (steps 6, 7).

Automate aspects of step 3.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

This project is only available as a Y3 project.

Initial literature for students:

  1. exomol.com
  2. http://pgopher.chm.bris.ac.uk/
  3. http://kkrk.chem.elte.hu/marvelonline/index.php
  4. gaussian.com

Novelty, degree of difficulty and amount of assistance required

Project is novel in that molecules to be studied is open-ended. The process of producing line lists by the ExoMol group (http://exomol.com/) is well developed.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Identification of molecules to study.end of October
Summary of available experimental data.Christmas
Step 8 detailed above.end of February
Steps 6 and 9 detailed above.Easter