Alessandra Ricca

Dr. Ricca is a computational chemist with over 25 years of experience in modeling the formation, reactivity, spectroscopy, and optical properties of organic compounds in the gas-phase and in ices. She is a leading contributor of theoretical PAH infrared spectra to the NASA Ames PAH IR Spectroscopic Database. 

Education:

B.S., December 1988, University of Geneva, Switzerland.

M.S., March 1989, University of Geneva, Switzerland.

Ph.D., Physical Chemistry, July 1993, University of Geneva, Switzerland.

Research Interests:

· Study the spectral characteristics of PAHs and nanograins in the interstellar medium and understand their photochemical evolution.

· Investigate the chemical processes occurring on interstellar dust grains coated with aromatics and H2O ices.

· Study the nature of ammonia-water ice species present on Charon and other icy bodies.

“Polycyclic aromatic hydrocarbons with straight edges and the 7.6/6.2 and 8.6/6.2 intensity ratios in reflection nebulae”, A. Ricca, C. W. Bauschlicher, J. E. Roser, E. Peeters, ApJ (2018) 854, 40.

“The NASA Ames PAH IR spectroscopic database: computational version 3.00 with updated content and the introduction of multiple scaling factors”, C. W. Bauschlicher, A. Ricca, C. Boersma et al., ApJS (2018) 234, 32.

“Infrared spectroscopy of matrix-isolated neutral and ionized anthracoronene in argon”, A. de Barros, A. L. Mattioda, J. M. Korsmeyer, A. Ricca, J. Phys. Chem. A (2018) 122, 2361.

“The PAH emission characteristics of the reflection nebula NGC 2013”, E. Peeters, C. W. Bauschlicher, L. J. Allamandola, A. G. G. M. Tielens, A. Ricca, M. Wolfire, ApJ (2017) 836, 198.

“Photochemistry of coronene in cosmic water ice analogs at different concentrations”, A. de Barros, A. L. Mattioda, A. Ricca, G. A. Cruz-Diaz, L. J. Allamandola, ApJ (2017) 848, 112.

“Infrared spectroscopy of matrix-isolated neutral polycyclic aromatic nitrogen heterocycles: The acridine series”, A. L. Mattioda, C. W. Bauschlicher, A. Ricca, J. Bregman, D. M. Hudgins, L. J. Allamandola, Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy (2017) 181, 286.

“Polycyclic aromatic hydrocarbon clusters as sources of interstellar infrared emission”, J. E. Roser & A. Ricca, ApJ (2015) 801, 108.

“Photochemistry of polycyclic aromatic hydrocarbons in cosmic water ice: the role of PAH ionization and concentration”, A. M. Cook, A. Ricca, A. L. Mattioda, J. Bouwman, J. E. Roser, H. Linnartz, J. Bregman, L. J. Allamandola, ApJ (2015) 799, 14.

“Anthracene clusters and the interstellar infrared emission features”, J. E. Roser, A. Ricca, L. J. Allamandola, ApJ (2014) 783, 97.

“The Organism/Organic Exposure to Orbital Stresses (O/OREOS) satellite: radiation exposure in low-earth orbit and supporting laboratory studies of iron tetraphenylporphyrin chloride”, A. M. Cook, A. L. Mattioda, A. J. Ricco, R. C. Quinn, A. Elsaesser, P. Ehrenfreund, A. Ricca, N. C. Jones, S. V. Hoffmann, Astrobiology (2014) 14, 87.

“The NASA Ames PAH IR spectroscopic database version 2.00: updated content, website, and on(off)line tools”, C. Boersma, C. W. Bauschlicher, A. Ricca, A. L. Mattioda, J.Cami, E.Peeters, F. Sanchez de Armas, G. Puerta Saborido, D. M. Hudgins, L. J. Allamandola, ApJS (2014) 211, 8.

“Loss of a C2Hnfragment from pyrene and circumcoronene”, C. W. Bauschlicher & A. Ricca, Theo. Chem. Acc. (2014), 133, 1479.

“The infrared spectra of C96H25compared with that of C96H24”, C. W. Bauschlicher & A. Ricca, Theo. Chem. Acc. (2014), 133, 1454.

“The structure, origin, and evolution of interstellar hydrocarbon grains”, J. E. Chiar, A.G. G. M. Tielens, A. J. Adamson, A. Ricca, ApJ (2013), 770, 78.

“Infrared Vibrational and Electronic Transitions in the Dibenzopolyacene Family”, A. L. Mattioda, C. W. Bauschlicher, J. Bregman, D. M. Hudgins, L. J. Allamandola, A Ricca, Spectrochim. Acta A (2013), 130, 639.

“The infrared spectroscopy of neutral polycyclic aromatic hydrocarbon clusters”, A. Ricca, C. W. Bauschlicher, L. J. Allamandola, ApJ (2013), 776, 31.

“The infrared spectra of polycyclic aromatic hydrocarbons with some or all hydrogen atoms removed”, C. W. Bauschlicher, A. Ricca, ApJ (2013), 776, 102.

“Naphthalene dimer and naphthalene dimer with Ar: calibration calculations and the effect of Ar on the stability and vibrational frequencies”, C. W. Bauschlicher & A. Ricca, Theo. Chem. Acc. (2013), 132, 1395.

“On the calculation of the vibrational frequencies of C6H4”, C. W. Bauschlicher & A. Ricca, Chem. Phys. Lett. (2013), 556, 1.

“The infrared spectroscopy of compact polycyclic aromatic hydrocarbons containing up to 384 carbons”, A. Ricca, C. W. Bauschlicher, C. Boersma, A. G. G. M. Tielens, L. J. Allamandola, ApJ (2012), 754, 75.

“Polycyclic aromatic hydrocarbon Far-infrared Spectroscopy”, C. Boersma, C. W. Bauschlicher, A. Ricca, A. L. Mattioda, E. Peeters, A. G. G. M. Tielens, L. J. Allamandola, ApJ (2011), 729, 64.

“The infrared spectroscopy of PAHs with 5,7-membered fused ring defects”, A. Ricca, C. W. Bauschlicher, L. J. Allamandola, ApJ (2011), 729, 94.

“Protonated PAH revisited”, A. Ricca, C. W. Bauschlicher, L. J. Allamandola, ApJ (2011), 727, 128.

“On the calculation of the vibrational frequencies of polycyclic aromatic hydrocarbons”, C. W. Bauschlicher, A. Ricca, Mol. Phys. (2010), 108, 2647.

“The NASA Ames PAH IR spectroscopic database: the computed spectra”, C. W. Bauschlicher, C. Boersma, A. Ricca, A. L. Mattioda, J. Cami, E. Peeters, F. Sanchez de Armas, G. Puerta Saborido, D. M. Hudgins, L. J. Allamandola, ApJS (2010) 189, 341.

“The Far-Infrared Spectroscopy of Very Large Neutral PAHs”, A. Ricca, C. W. Bauschlicher, A. L. Mattioda, L. J. Allamandola, ApJ 709, 42 (2010).

“The 15 – 20 µm PAH emission features: probes of individual PAHs?”, C. Boersma, C. W. Bauschlicher, L. J. Allamandola, A. Ricca, E. Peeters, A. G. G. M. Tielens, A&A, 511, A32 (2010).

“The far-infrared emission from the Mg+-PAH species”, C. W. Bauschlicher & A. Ricca, ApJ 698, 275-280 (2009).

“Far-infrared spectroscopy of neutral coronene, ovalene, and dicoronylene”, A. L. Mattioda, A. Ricca, J. Tucker, C. W. Bauschlicher, L. J. Allamandola, Astronom. J. 137, 4054 (2009).

“Formation of complex organics from acetylene catalyzed by ionized benezene”, P. O. Momoh, A. Soliman, M. S. El-Shall, A. Ricca, J. Am. Chem. Soc. 130, 12848 (2008).

“The gas-phase catalytic formation of H2by cations” A, Ricca & C. W. Bauschlicher, Chem. Phys. Lett. 463, 327 (2008).

“Electronic and Vibrational Spectroscopy of Diamondoids and the Interstellar Infrared bands between 3.35 and 3.55 microns”, C. W. Bauschlicher, Y. Liu, A. Ricca, A. L. Mattioda, L. J. Allamandola, ApJ 671, 458 (2007).

“The energetics for hydrogen addition to naphthalene cations”, A. Ricca, E. L. O. Bakes, C. W. Bauschlicher, ApJ 659, 858 (2007).

“Mechanisms for the growth of polycyclic aromatic hydrocarbon (PAH) cations”, C. W. Bauschlicher, A. Ricca, M. Rosi, Chem. Phys. Lett. 355,159 (2002).

“Mechanisms for the incorporation of a nitrogen atom into polycyclic aromatic hydrocarbon cations”, A. Ricca, C. W. Bauschlicher, M. Rosi, Chem. Phys. Lett. 347, 473 (2001).

“On the reaction CH2O + NH3→ CH2NH + H2O”, S. P. Walch, C. W. Bauschlicher, A. Ricca, E. L. O. Bakes, Chem. Phys. Lett. 333, 6 (2001).

“Mechanisms for the incorporation of a nitrogen atom into polycyclic aromatic hydrocarbons”, A. Ricca, C. W. Bauschlicher, E. L. O. Bakes, Icarus 154, 516 (2001).

“The reactions of polycyclic aromatic hydrocarbons with OH”, A. Ricca & C. W. Bauschlicher, Chem. Phys. Lett. 328, 396 (2000).

“Mechanisms for polycyclic aromatic hydrocarbon (PAH) growth”, C. W. Bauschlicher & A. Ricca, Chem. Phys. Lett. 326, 283 (2000).

PAH Infrared Spectroscopy in the JWST Era

Grant #: NNX17AE71G

 

 

The extraordinary infrared instruments on the James Webb Space Telescope (JWST) will transform the field of cosmic spectroscopy. We propose to supply the astronomical community with theoretical and experimental spectra of a wide range of Polycyclic Aromatic Hydrocarbons (PAHs) and PAH clusters and to use our IR absorption spectra to calculate emission spectra that will be crucial in interpreting the new observational data. 

The Infrared Space Observatory and Spitzer Space Telescopes have shown that the mid-IR emission spectrum of the interstellar  medium is dominated by strong bands at 3.3, 6.2, 7.7, 8.6, 11.3 and 12.7 microns superimposed upon broad underlying plateaus generally attributed to PAHs, PAH clusters and very small grains. Despite the limited spectral and spatial resolution of these data, detailed analysis has revealed that each band is, in fact, a blend of multiple emission features. Subtle variations in the band blending can be detected even for spectra measured at different positions within a single astronomical source. These variations can be seen to arise from multiple PAH and PAH-related carriers that are each responding differently to the local physical conditions. The James Webb Space Telescope has near-IR and mid-IR instruments, NIRSpec and MIRI, with an extremely high spectral resolution, spatial resolution, and sensitivity that will revolutionize infrared astronomy. These instruments will provide spatial maps on a sub-arcsecond scale with an unprecedented level of spectral detail, allowing detailed study of the interrelationship of the individual components within each emission band. This will provide a critical insight into the molecular characteristics of the emitting species and their photochemical evolution in space.

Exploitation of these astronomical spectra requires fundamental data on potential emitting species that fully account for all astrophysically relevant materials. Over the last two decades, spectra of neutral and charged PAHs have been calculated using quantum theory. Due to computational limitations, this data set is biased towards smaller or highly symmetric species. In addition,  continued analysis of the mid-IR emission bands by several recent Spitzer studies, has demonstrated that PAHs and PAH clusters with less symmetric structures containing “bay regions” are more important for understanding the IR emission bands than had  previously been realized. The currently available infrared data set on less symmetric PAHs and PAH clusters is insufficient to exploit the astronomical data.

Advances in computing power now allow spectra for a much wider range of species to be calculated. In support of the analysis of Spitzer data and the upcoming JWST mission, we therefore propose to calculate the 3-20 micron spectra of isolated as well as clustered neutral and charged PAHs containing up to 150 carbon atoms and with a wide range of compact structures and eroded structures with irregular shapes containing “bay regions”, “coves”, and “fjords”. These theoretical data will be validated by a dedicated laboratory study of PAH species and their clusters. These IR absorption spectra will be used to calculate emission spectra that can be directly compared to existing astronomical observations and that will be used to guide our quantum chemical and experimental studies on relevant species for support of Early Release Science proposals for JWST.

 

 

Ammonia on Charon: A Laboratory Study of Ammonia Hydrates in Support of New Horizons Observations

Grant #: 80NSSC18K0007

 

Science Goals and Objectives 

Recent New Horizons results and ground-based observations support the presence of NH₃on the surface of Charon, Pluto’s largest moon. NH₃has also been found on the surfaces of the smaller moons Nix and Hydra as well as on the surfaces of Orcus and Quaoar.  This is unusual since NH₃should not survive on the surface of these icy bodies for longer than a few million years due to the proton radiation flux in the Outer Solar System. As of today, no mechanism for preserving NH₃on the surface of these bodies has been accepted as definitive. 

For Charon, mechanisms such as cryovolcanism have been suggested to explain the presence of this ice but these are not consistent with a moon too small to sustain a submerged liquid ocean. Another possible explanation is that NH₃is one of the primordial constituents of Charon. Subsurface NH₃would then be diffusing up into Charon’s surface H₂O ice layer. Based upon the broadened shape of Charon’s 2.21 µm band, NH₃also appears to be complexed in H₂O in different ways and in different amounts, thus adding to the uncertainty of its origin.

This proposal seeks to improve our understanding of the stability of NH₃/H₂O ices as a function of ice structure, concentration, and temperature, and to provide near-IR spectral data of NH₃in H₂O ices that will be critical for the interpretation of observations of outer Solar System bodies. 

Methodology

The experimental work will be performed in the NASA Ames Astrochemistry Laboratory and will consist of a series of near-IR spectral measurements of H₂O/NH₃ices conducted using transmission-reflection spectroscopy. Most of the equipment needed to perform the transmission-reflection spectroscopy of thin films is already available in the Astrochemistry Laboratory.

Calibration experiments will be carried out with simultaneously deposited ice mixtures as a function of the NH₃concentration relative to H₂O. The sample deposition temperature will also be probed since this is expected to strongly affect the amorphous vs. crystalline structure of the H₂O ice.

Experiments will then continue with spectroscopy of ``sandwich layers” of NH₃deposited between a base layer of crystalline H₂O ice and an over-layer of amorphous H₂O ice deposited at various substrate temperatures. Spectroscopy of these ice deposits after deposition and during a subsequent warm-up will simulate the stochastic process of an interior reservoir of NH₃molecules diffusing upwards into Charon’s partially amorphized surface layer.

Theoretical calculations will be performed as needed to help in the interpretation of the laboratory data. 

Relevance

This proposal is relevant to the Solar System Workings program because it seeks to characterize and understand the stability of NH₃on the surface of icy outer Solar System bodies and will also provide relevant near-IR spectral data of NH₃in H₂O ices that will be critical for the interpretation of New Horizons observations. This research is therefore highly relevant to the Solar System Workings program since it is precisely the study of ``evolution and modification of surfaces” mandated by the “Surfaces and Interiors” section.