Chemical evolution observational aspects

The study of galactic evolution thus comprises two aspects. One is of an observational nature, wherein abundances are assessed in stars of various generations, by means of spectral analysis. The other is purely theoretical, involving numerical simulation of the chemical evolution of the interstellar medium in which stars are born. 

COMMENTARY OBSERVATIONAL ASPECTS RELATED TO THE CHEMICAL EVOLUTION OF OUR ATMOSPHERE... 

In line with the spirit of this book, I will present mainly the highlights of our contributions and those of other laboratories on this subject, with autobiographical comments, following an approximate chronological order. I will leave aside the general aspects of the theory of chemical evolution and will mention briefly some of the more specific observations of organic molecules in interstellar space and comets. 

The important effect of increasing pressure on the kinetics of chemical reactions has been noted since the hrst chemical experiments at high pressure. The simplest expectation derives from the observation that in liquids the viscosity rapidly increases with pressure. As a result, in strongly compressed liquids, and hnally in glasses, diffusion-controlled processes can be retarded. In contrast, however, other reaction pathways can be substantially accelerated. In general, the evolution of a reaction at high pressure can be heavily controlled by kinetic aspects, and these deeply involve intermolecular effects. 

In addition to chemical compositions, another important aspect about SEI formation that is of practical significance to the forming of lithium ion cells is the potential range in which the above reactions occur leading to the formation of the SEI. Because of the earlier observation of the plateau near 0.80 and the concurrent gas evolution, it... 

Titan, the largest satellite of Saturn, is one of tlie smallest known bodies with an atmosphere. The Voyager observation provided information on Titan s atmosphere, and the origin and evolution of the Titan s atmosphere have been discussed from many aspects. Titan can be used to simulate planetary-scale chemical activity and surface-atmosphere interactions in tlie absence of tlie influence... 

---