Astrochemistry: From The Big Bang To The Present Day

by Claire Vallance

Overview

'This book could appeal to astronomers interested in interstellar and circumstellar matter who would like to know more about the processes in them from a chemist's perspective in a modern textbook. Overall, I found this book very informative and clearly written …'
The Observatory MagazineThe rapidly growing field of astrochemistry focuses on the chemistry occurring in stars, planets, and the interstellar medium, bringing together elements of chemistry, physics, astrophysics, and biology. Astrochemistry describes the chemical history of the Universe, our solar system, and our planet. It explores in some detail the 'alien' chemistry occurring in interstellar gas clouds, the regions where stars and planets are formed, and also looks at the theoretical and experimental methods that allow us to carry out Earth-based studies of astrochemistry.The evolution of the Universe and the complex chemistry occurring both in interstellar space and in the planetary systems that form in these regions is explained primarily in terms of basic principles of physical chemistry. While there is plenty to interest the general reader, this book is aimed at intermediate to advanced undergraduates of chemistry and astrochemistry, highlighting many different aspects of physical chemistry and demonstrating their relevance to the world we live in.This book was written in conjunction with Atmospheric Chemistry: From the Surface to the Stratosphere, Grant Ritchie (2017) World Scientific Publishing.

Product Details

ISBN-13:	9781786340382
Publisher:	World Scientific Publishing Europe Ltd
Publication date:	04/19/2017
Series:	Essential Textbooks In Chemistry
Edition description:	Reprint
Pages:	228
Product dimensions:	6.00(w) x 8.90(h) x 0.40(d)

Table of Contents

Preface v

Author Biography vii

Acknowledgements ix

List of Figures xvii

List of Tables xxiii

1 Measuring the Universe 1

1.1 Studying the Universe via spectroscopy 1

1.1.1 Line positions 1

1.1.2 Line intensities 3

1.1.3 Principle of operation of an astronomical spectrograph 4

1.1.4 Spectral windows for Earth-based observations 4

1.2 Döppler shift 5

1.3 Döppler lineshape 6

1.4 Döppler shift, the Hubble constant, and the age of the Universe 7

1.5 Questions 8

1.5.1 Essay-style questions 8

1.5.2 Problems 9

2 From the Big Bang to the First Atoms 11

2.1 The very early Universe: The building blocks of matter 11

2.2 The nature of the expanding Universe 11

2.3 The first particles 13

2.4 Hydrogen and helium nuclei 15

2.5 The first atoms 15

2.6 Questions 16

2.6.1 Essay-style questions 16

2.6.2 Problems 16

3 Stars and the Creation of the Higher Elements 19

3.1 Star formation and the nucleosynthesis of heavier elements 19

3.2 Dispersion of the chemical elements into interstellar space 23

3.3 Cosmic abundance of the elements 25

3.4 Questions 26

3.4.1 Essay-style questions 26

3.4.2 Problems 26

4 Interstellar Chemistry - Molecules in Space 29

4.1 The interstellar medium 29

4.1.1 Diffuse interstellar medium 29

4.1.2 Giant molecular clouds 30

4.1.3 Circumstellar medium 32

4.2 Chemistry in interstellar space 32

4.3 Molecular synthesis in interstellar gas clouds 34

4.4 Ionisation processes in the interstellar medium 34

4.5 Gas-phase chemical reactions in the interstellar medium 36

4.6 Bond-forming reactions 36

4.6.1 Radiative association 36

4.6.2 Associative detachment 37

4.6.3 Dust-grain-catalysed reactions 37

4.7 Bond breaking reactions 38

4.7.1 Photodissociation and collisional dissociation 38

4.7.2 Dissociative recombination 39

4.8 Rearrangement reactions 39

4.8.1 Charge transfer 39

4.8.2 Neutral reactions 40

4.8.3 Ion-molecule reactions 40

4.8.3.1 Hydrogen atom abstraction 40

4.8.3.2 Proton transfer 41

4.8.3.3 Carbon insertion 41

4.8.3.4 Rearrangement reactions 42

4.9 Neutralisation processes in the interstellar medium 42

4.10 Summary 43

4.11 Questions 43

4.11.1 Essay-style questions 43

4.11.2 Problems 44

5 Laboratory-Based Astrochemistry: Theory 47

5.1 Lab oratory-based astrochemistry 47

5.2 The grand challenge: Chemical modelling of giant molecular clouds 48

5.2.1 The search for biological molecules 49

5.2.2 The diffuse interstellar bands (DIBs) 50

5.3 Theoretical astrochemistry I: Spectroscopic data 51

5.3.1 Rotational transition frequencies 53

5.3.2 Vibrational transition frequencies 55

5.3.3 Electronic transition frequencies 58

5.3.4 Transition intensities 58

5.4 Theoretical astrochemistry II: Kinetic and dynamical data 59

5.4.1 Types of collision 60

5.4.2 Relative velocity 60

5.4.3 Collision energy, total kinetic energy, and conservation of linear momentum 61

5.4.4 Conservation of energy and energy available to the products 62

5.4.5 Impact parameter, b, and opacity function, P(b) 62

5.4.6 Collision cross-section, σ_c 63

5.4.7 Reaction cross-section, σ_r 64

5.4.8 The excitation function, σ_r(E_coll), and the thermal rate constant, k(T) 65

5.4.8.1 Exoergic with no barrier 66

5.4.8.2 Endoergic or exoergic with a barrier 67

5.4.9 Orbital angular momentum, L, and conservation of angular momentum 67

5.4.10 The interaction potential and its effect on the collision cross-section 69

5.4.11 Atomic and molecular interactions 71

5.4.12 The potential energy surface for a polyatomic system 71

5.4.13 Construction of the potential energy surface 73

5.4.14 The potential energy surface and the collision dynamics 73

5.4.15 The potential energy surface for a linear triatomic system 75

5.4.16 Reactive and non-reactive trajectories across the potential energy surface 77

5.4.17 General features of potential energy surfaces 79

5.4.18 Examples of potential energy surfaces for real chemical systems 80

5.4.18.1 The simplest chemical reaction: H + H₂ → H₂ + H 80

5.4.18.2 Photodissociation of NO₂ 81

5.4.18.3 H + CO₂ → OH + CO and OH + SO → H + SO₂ 82

5.4.18.4 The Ar + H⁺₂ → ArH⁺ + H reaction 82

5.4.19 Orbital angular momentum, centrifugal barriers and the effective potential 84

5.4.20 A simple model for the rate of ion- molecule reactions 85

5.4.21 Reaction cross-sections from quasi-classical trajectory calculations 89

5.5 Summary 89

5.6 Questions 90

5.6 1 Essay-style questions 90

5.6.2 Problems 90

6 Laboratory-Based Astrochemistry: Experiment 97

6.1 Experimental astrochemistry I: Spectroscopic data 97

6.1.1 Molecular beams 98

6.1.1.1 Effusive sources 99

6.1.1.2 Supersonic sources 100

6.1.2 Fourier-transform microwave spectroscopy 102

6.1.3 Laser-induced fluorescence 103

6.1.4 Resonance-enhanced multiphoton ionization (REM PI) 104

6.1.5 Cavity-enhanced absorption spectroscopy methods 106

6.1.5.1 Cavity ring-down spectroscopy 107

6.1.5.2 Cavity-enhancod absorption spectroscopy 109

6.1.6 Molecular size considerations 110

6.2 Experimental astro chemistry II: Gas-phase kinetic and dynamical data 111

6.2.1 Ion cyclotron resonance mass spectrometry 112

6.2.1.1 The km cyclotron resonance technique 112

6.2.1.2 Measuring ion-molecule rate constants via ICR-MS 115

6.2.2 The flowing afterglow technique 116

6.2.3 The selected-ion flow tube 117

6.2.4 The CRESU method 117

6.2.5 Coulomb crystals 118

6.2.6 Neutral reactions 120

6.3 Experimental astrochemistry III: Dust-grain chemistry 121

6.3.1 Ice structures via infrared spectroscopy 121

6.3.2 Thermodynamics of adsorption and desorption via temperature-programmed desorption 123

6.3.3 Photoinitiated molecular synthesis in interstellar ice analogues 124

6.3.4 Formation of H₂ on ice surfaces 124

6.4 Case study: Ethylene glycol 125

6.5 Summary 129

6.6 Questions 129

6.6.1 Essay-style questions 129

6.6.2 Problems 130

7 Formation of the Solar System and the Evolution of Earth 135

7.1 The Solar nebula 136

7.2 The protoplanetary disk 138

7.3 Formation of the planets 138

7.4 The early Earth, and formation of the Moon 143

7.4.1 The Moon's orbit and tidal locking 145

7.5 The layered structure of the Earth 147

7.5.1 The core and the Earth's magnetic field 148

7.5.2 The mantle 149

7.5.3 The crust 152

7.5.3.1 Divergent plate boundaries 153

7.5.3.2 Convergent plate boundaries 153

7.5.4 The primordial atmosphere 155

7.6 Oceans and tides 155

7.7 Erosion and weathering 158

7.8 Life and the oxygen atmosphere 160

7.9 Fossilisation and fossil fuels 164

7.10 Other Solar systems 166

7.11 Further reading 169

7.12 Questions 169

7.12.1 Essay-style questions 169

7.12.2 Problems 170

Appendix A Rates of Chemical Reactions 175

A.1 Reactions occurring in a single step 175

A.2 Reactions occurring in multiple steps 177

A.3 Experimental kinetics studies 179

Appendix B The Variation Principle and the Linear Variation Method 181

B.1 The variation principle 181

B.2 The linear variation method 182

Appendix C Mass-Weighted Coordinates and the Skew Angle 185

Answers to Numerical Problems 189

Index 195