Alessandra Ricca

Alessandra Ricca
Computational Chemist
Curriculum Vitae: 

Alessandra Ricca is a computational chemist who is interested in the formation of complex organic molecules, such as nitrogenated aromatic heterocycles, in various environments, ranging from outflows of carbon-rich stars to Titan’s haze and the early Earth. Heterocycles containing nitrogen atoms, such as pyrroles and pyrimidines, are among the building blocks of life. Understanding how they are formed is of fundamental importance to astrobiology.

Alessandra is also involved in the computation of the spectral properties of carbonaceous molecular species to help interpret data obtained by various NASA missions, such as the Spitzer Space Telescope and the Stratospheric Observatory for Infrared Astronomy (SOFIA).

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Tracing Aromatic Carbon's Cosmic Evolution

The origin of carbonaceous matter starts with the injection of atoms, molecules and dust into interstellar space by C-rich, late type stars. There it is processed by ultraviolet radiation, energetic particles and shocks. Some of this material becomes incorporated into dense molecular clouds and fuels new stars and their emerging planetary systems. Observations over the past twenty years, combined with quantum chemical calculations and laboratory experiments have shown that aromatic materials are a very important component of interstellar matter. This proposal aims to shed light on the detailed chemistry and spectroscopy of cosmic aromatic materials.

The Carbon Dioxide Infrared Absorption Bands: Probes of the Chemistry on the Surface of Planetary Bodies

CO2 is observed on Mars and on the moons of Jupiter and Saturn, and it is highly likely that it is to be found elsewhere among the outer planets. One of the most interesting occurrences of CO2 is inside water ice, where the observed CO2 vibrational band is shifted relative to that of the gas-phase or solid-phase CO2. Of even more interest is the fact that the position of the CO2 asymmetric stretching band varies from satellite to satellite. While laboratory work has yielded some insight into the change in CO2 frequency with water environment, there is still much to be learned; a difficult task because of the complexity of the system. Here we propose to simulate the vibration of CO2 inside various forms of water ice, from crystalline to amorphous and to clathrates. These calculations will yield sufficient insight into the correlation between the water environment at the molecular level and the observed CO2 vibrational frequency to aid in the interpretation of the laboratory experiments and the observations. One should then be able to deduce information about the nature of the water ice on the outer planets, yielding insight into its formation and history.

The Formation and Detection of Biogenic Aromatics in Dense Molecular Clouds around Embedded Protostars

This work involves building a database of the spectra of aromatic compounds, for use in interpreting astronomical observations and in developing instrumentation for planetary landers and probes. We are pursuing collaborations in this area with other scientists at NASA, universities, and non-profits.

PAH database website

The NASA Ames PAH IR Spectroscopic Database: PAH Spectroscopy at Your Fingertips

This work involves building a database of the spectra of aromatic compounds, for use in interpreting astronomical observations and in developing instrumentation for planetary landers and probes. We are pursuing collaborations in this area with other scientists at NASA, universities, and non-profits.