Physics projects for Y3 and Y4 students

Project description

Diatomic molecules in sunspots: MARVEL and DC analysis of BaO

(supervisor: Maire Gorman)

Nature of project: data analysis, software

Available to students on full-time physics degree schemes 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.

Many diatomic molecules have been discovered in sunspots: they are of interest to astronomers as their spectra could theoretically give better indications of temperature, pressure and magnetic field compared to traditional atomic diagnostics.

The aim of this project is to compile, analyse and compare experimentally determined data on BaO.

Diatomic Constants (DCs) are constants fitted by experimentalists which can be used to generate a list of energies. One potential drawback with DCs is that they do not take into account perturbations and interactions between electronic states within a molecule.

MARVEL analysis can potentially circumvent this issue: the process involves using online software to build "spectroscopic networks" of energy levels from experimentally measured wavelengths.

The list of energies produced by using DCs and MARVEL process can be compared.

A successful project will develop beyond the above in one/some of the following directions:
As baseline I would expect student to undertake analysis of ground and one excited electronic state. More ambitous students can aim to abalyse all electronic states (~5) for which experimental data is available.

A different type of work would be to then fit potential energy curves to derived energy levels using Duo programme. This is a challenging type of fitting.

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.

Additional scope or challenge if taken as a Year-4 project: Ab initio calculations of electronic curves using MOLPRO software.

Please speak to Maire Gorman if you consider doing this project.

Initial literature for students:

  1. http://kkrk.chem.elte.hu/marvelonline/index.php
  2. MARVEL Analysis of the Measured High-resolution Rovibronic Spectra of 90Zr160, McKemmish et al. (2018), The Astrophysical Journal, 867:33.
  3. A Detailed Analysis of Barium Oxide Molecular Lines in Sunspot Umbral Spectra, Shanmugapriya et al. (2015), Solar Physics 290(6):1569-1579
  4. Identification of barium oxide and halides in late-type stars, Dubois (1977), Astronomy and Astrophysics, Vol. 57, p. 51-54

Novelty, degree of difficulty and amount of assistance required

MARVEL projects have successfully been done for TiO, ZrO and also for C2H2 by collaborators (see references).

Project milestones and deliverables (including timescale)

milestoneto be completed by
Overview diagram of experimental data availableChristmas
Collection of spectroscopic constants and Dunham analysisend of February
MARVEL analysis of ground electronic statemid-March
MARVEL analysis of upper electronic systemsEaster