Suggested Searches

Modeling Laboratory


Member: Alessandra Ricca


Objectives:

  • Characterize the infrared, Raman, and UV-Vis spectral characteristics of astrophysically-relevant polycyclic aromatic hydrocarbons (PAHs), clusters, and nanograins, and study their photochemical evolution in the interstellar medium, dense clouds, and on planetary surfaces.
  • Compute near-IR spectral signatures of planetary ice analogs for Pluto and Charon surface studies.
  • Model the formation of gas-phase molecules in planetary atmospheres.

Facilities:


The High-End Computing Capability (HECC) at the NASA Advanced Supercomputing (NAS) Division of NASA Ames Research Center provides:

  • World-class computing
  • Storage
  • Visualization resources

Software:

  • Gaussian16
  • Molpro
  • VASP
  • LAMMPS
  • Octopus

Objective 1. Characterize the infrared (IR), Raman, and UV-Vis spectral characteristics of astrophysically-relevant polycyclic aromatic hydrocarbons (PAHs), clusters, and nanograins, and study their photochemical evolution in the interstellar medium, dense clouds, and on planetary surfaces.

Fig. 1: The charge-size grid for radiation fields with an average photon energy of 10 eV
Fig. 1: The charge-size grid for radiation fields with an average photon energy of 10 eV

Methodology:

  • Compute the zero-Kelvin absorption spectra (IR, Raman, UV-Vis)
  • Compare the computed absorption spectra with JWST data of Young Stellar Objects (YSOs)
  • Compute emission spectra and compare with SOFIA and JWST data of astrophysical sources, constrain the emitters of the astrophysical 3-20 microns IR bands and link the variations of the observed features to PAH size and charge (Fig. 1)
  • Understand the photochemical evolution of the PAH populations in the interstellar medium (Fig. 2), dense clouds, and planetary surfaces

 Missions supported: SOFIA, JWST, Cassini, New Horizons

Fig. 2: Schematic of the photochemical evolution of the interstellar PAH population in NGC 2023

Objective 2. Compute near-IR spectral signatures of planetary ice analogs for Pluto and Charon surface studies.

Methodology:

  • Compute the zero-Kelvin near-IR anharmonic absorption spectra of pure and mixed ices relevant to Pluto and Charon
  • Correlate changes in spectral features with chemical composition, mixing ratios, crystallinity
  • Compare the computed spectra with available laboratory data and New Horizons data (Fig. 3).

Mission supported: New Horizons

Fig. 3: (Left panel): A contour map of Charon at 2.21 mm with selected regions numbered. (Right panel): New Horizons spectra (wh

Objective 3. Model the formation of gas-phase molecules in planetary atmospheres and exoplanets.

Methodology:

  • Compute accurate gas-phase reaction pathways, rate coefficients, and thermodynamic properties
  • Interpret mission data

Missions supported: TESS, JWST, WFIRST

List of publications here.