MOBILITY OF COMPLEX ORGANIC SPECIES AT METAL SURFACES

2006 ◽  
pp. 269-286 ◽  
Author(s):  
JOHANNES V. BARTH
Keyword(s):  
Metal Surfaces ◽  
Organic Species ◽  
Complex Organic

scholarly journals Laboratory and Modeling Studies of Chemistry in Dense Molecular Clouds

1980 ◽  
Vol 87 ◽  
pp. 331-336
Author(s):  
W.T. Huntress ◽  
S. S. Prasad ◽  
G. F. Mitchell
Keyword(s):  
Chemical Equilibrium ◽  
Molecular Clouds ◽  
Evolutionary Model ◽  
Chemical Processes ◽  
Chemical Library ◽  
Interstellar Clouds ◽  
Organic Species ◽  
Radiative Association ◽  
Simple Chemical ◽  
Complex Organic

A chemical evolutionary model with a large number of species and a large chemical library is used to examine the principal chemical processes in interstellar clouds. Simple chemical equilibrium arguments show the potential for synthesis of very complex organic species by ion-molecule radiative association reactions.

scholarly journals Chemical changes during transport from cloud to disk

2008 ◽  
Vol 4 (S251) ◽  
pp. 111-116
Author(s):  
Ruud Visser ◽  
Ewine F. van Dishoeck ◽  
Steven D. Doty
Keyword(s):  
Solid Phase ◽  
Time Dependent ◽  
Temperature Structure ◽  
Mass Star ◽  
Full Time ◽  
Form Complex ◽  
Organic Species ◽  
Starting Point ◽  
Low Mass ◽  
Complex Organic

AbstractWe present the first semi-analytical model that follows the chemical evolution during the collapse of a molecular cloud and the formation of a low-mass star and the surrounding disk. It computes infall trajectories from any starting point in the cloud and it includes a full time-dependent treatment of the temperature structure. We focus here on the freeze-out and desorption of CO and H2O. Both species deplete towards the centre before the collapse begins. CO evaporates during the infall phase and re-adsorbs when it enters the disk. H2O remains in the solid phase everywhere, except within a few AU of the star. Material that ends up in the planet- and comet-forming zones is predicted to spend enough time in a warm zone during the collapse to form complex organic species.

scholarly journals The ALMA-PILS survey: the first detection of doubly deuterated methyl formate (CHD2OCHO) in the ISM

2019 ◽  
Vol 623 ◽  
pp. A69 ◽  
Author(s):  
S. Manigand ◽  
H. Calcutt ◽  
J. K. Jørgensen ◽  
V. Taquet ◽  
H. S. P. Müller ◽  
...  
Keyword(s):  
Star Formation ◽  
Organic Molecules ◽  
Methyl Formate ◽  
Local Thermal Equilibrium ◽  
Organic Species ◽  
Physical Conditions ◽  
Methyl Cyanide ◽  
Model Tracing ◽  
Star Formation Regions ◽  
Complex Organic

Studies of deuterated isotopologues of complex organic molecules can provide important constraints on their origin in star formation regions. In particular, the abundances of deuterated species are very sensitive to the physical conditions in the environment where they form. Because the temperatures in star formation regions are low, these isotopologues are enhanced to significant levels, which enables the detection of multiply deuterated species. However, for complex organic species, so far only the multiply deuterated variants of methanol and methyl cyanide have been reported. The aim of this paper is to initiate the characterisation of multiply deuterated variants of complex organic species with the first detection of doubly deuterated methyl formate, CHD2OCHO. We use ALMA observations from the Protostellar Interferometric Line Survey (PILS) of the protostellar binary IRAS 16293–2422 in the spectral range of 329.1 GHz to 362.9 GHz. Spectra towards each of the two protostars are extracted and analysed using a local thermal equilibrium model in order to derive the abundances of methyl formate and its deuterated variants. We report the first detection of doubly deuterated methyl formate CHD2OCHO in the ISM. The D-to-H ratio (D/H ratio) of CHD2OCHO is found to be 2–3 times higher than the D/H ratio of CH2DOCHO for both sources, similar to the results for formaldehyde from the same dataset. The observations are compared to a gas-grain chemical network coupled to a dynamical physical model, tracing the evolution of a molecular cloud until the end of the Class 0 protostellar stage. The overall D/H ratio enhancements found in the observations are of about the same magnitude as the predictions from the model for the early stages of Class 0 protostars. However, that the D/H ratio of CHD2OCHO is higher than that of CH2DOCHO is still not predicted by the model. This suggests that a mechanism enhances the D/H ratio of singly and doubly deuterated methyl formate that is not in the model, for instance, mechanisms for H–D substitutions. This new detection provides an important constraint on the formation routes of methyl formate and outlines a path forward in terms of using these ratios to determine the formation of organic molecules through observations of differently deuterated isotopologues towards embedded protostars.

scholarly journals Did a Complex Carbon Cycle Operate in the Inner Solar System?

2020 ◽  
Author(s):  
Joseph A. Nuth ◽  
Frank Ferguson ◽  
Hugh Hill ◽  
Natasha Johnson
Keyword(s):  
Carbon Source ◽  
Gas Phase ◽  
Solar Nebula ◽  
Organic Content ◽  
Organic Species ◽  
Refractory Oxides ◽  
Volatile Products ◽  
Intimate Mixture ◽  
Complex Carbon ◽  
Complex Organic

Solids in the interstellar medium consist of an intimate mixture of silicate and carbonaceous grains. Because 99% of silicates in meteorites were reprocessed at high temperatures in the inner regions of the Solar Nebula, we propose that similar levels of heating of carbonaceous materials in the oxygen-rich Solar Nebula would have converted nearly all carbon in dust and grain coatings to CO. We discuss catalytic experiments on a variety of grain surfaces that not only produce gas-phase species such as CH4, C2H6, C6H6, C6H5OH or CH3CN, but also produce carbonaceous solids and fibers that would be much more readily incorporated into growing planetesimals. CO and other more volatile products of these surface mediated reactions were likely transported outwards along with chondrule fragments and small Calcium Aluminum Inclusions (CAIs) to enhance the organic content in the outer regions of the nebula where comets formed. Carbonaceous fibers formed on the surfaces of refractory oxides may have significantly improved the aggregation efficiency of chondrules and CAIs. Carbonaceous fibers incorporated into chondritic parent bodies might have served as the carbon source for the generation of more complex organic species during thermal or hydrous metamorphic processes on the evolving asteroid.

scholarly journals Did a Complex Carbon Cycle Operate in the Inner Solar System?

Life ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 206
Author(s):  
Joseph A. Nuth ◽  
Frank T. Ferguson ◽  
Hugh G. M. Hill ◽  
Natasha M. Johnson
Keyword(s):  
Carbon Source ◽  
Gas Phase ◽  
Solar Nebula ◽  
Organic Content ◽  
Organic Species ◽  
Refractory Oxides ◽  
Volatile Products ◽  
Intimate Mixture ◽  
Complex Carbon ◽  
Complex Organic

Solids in the interstellar medium consist of an intimate mixture of silicate and carbonaceous grains. Because 99% of silicates in meteorites were reprocessed at high temperatures in the inner regions of the Solar Nebula, we propose that similar levels of heating of carbonaceous materials in the oxygen-rich Solar Nebula would have converted nearly all carbon in dust and grain coatings to CO. We discuss catalytic experiments on a variety of grain surfaces that not only produce gas phase species such as CH4, C2H6, C6H6, C6H5OH, or CH3CN, but also produce carbonaceous solids and fibers that would be much more readily incorporated into growing planetesimals. CH4 and other more volatile products of these surface-mediated reactions were likely transported outwards along with chondrule fragments and small Calcium Aluminum-rich Inclusions (CAIs) to enhance the organic content in the outer regions of the nebula where comets formed. Carbonaceous fibers formed on the surfaces of refractory oxides may have significantly improved the aggregation efficiency of chondrules and CAIs. Carbonaceous fibers incorporated into chondritic parent bodies might have served as the carbon source for the generation of more complex organic species during thermal or hydrous metamorphic processes on the evolving asteroid.

Photochemical Evolution of Interstellar/Precometary Organic Material

1997 ◽  
Vol 161 ◽  
pp. 23-47 ◽  
Author(s):  
Louis J. Allamandola ◽  
Max P. Bernstein ◽  
Scott A. Sandford
Keyword(s):  
Origin Of Life ◽  
Building Blocks ◽  
Complex Species ◽  
Infrared Observations ◽  
Interstellar Ice ◽  
Polycyclic Aromatic ◽  
Ultraviolet Photolysis ◽  
The Origin Of Life ◽  
Simple Molecules ◽  
Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

The Wear of Metal Surfaces

1876 ◽  
Vol 1 (5supp) ◽  
pp. 78-78
Author(s):  
Joshua Rose
Keyword(s):  
Metal Surfaces
Sign in / Sign up

Export Citation Format

Share Document