Laboratory Astrochemistry: From Molecules through Nanoparticles to Grains

Written by leading scientists in the field and intended for a broader readership, this is an ideal starting point for an overview of current research and developments. As such, the book covers a broad spectrum of laboratory astrophysics and chemistry, describing recent advances in experiments, as well as theoretical work, including fundamental physics and modeling chemical networks. For researchers as well as students and newcomers to the field.

Table of Contents:
List of Contributors XIII Preface XIX 1 The Astrophysical Background 1 Malcolm Walmsley 1.1 The Contents of this Volume 8 References 11 2 Molecular Spectroscopy 13 Thomas Giesen 2.1 Electronic Spectroscopy of Potential Carriers of Diffuse Interstellar Bands 15 Corey A. Rice and John P. Maier 2.1.1 Introduction 15 2.1.2 Laboratory Methods 16 2.1.3 Species of Astrophysical Interest 19 2.1.4 Outlook 28 Acknowledgments 29 2.2 UV–Vis Gas-Phase Absorption Spectroscopy of PAHs 29 Yvain Carpentier, Gaël Rouillé, Mathias Steglich, Cornelia Jäger, Thomas Henning, and Friedrich Huisken 2.2.1 Introduction 29 2.2.2 Experimental 32 2.2.3 Data Analysis 36 2.2.4 Results and Discussion 40 2.2.5 Conclusion 48 Acknowledgments 49 2.3 Laboratory IR Spectroscopy of PAHs 49 Jos Oomens, Olivier Pirali, and Alexander G.G.M. Tielens 2.3.1 Introduction 49 2.3.2 Laboratory Spectroscopic Methods 52 2.3.3 Far-Infrared Spectroscopy 60 2.3.4 IR Spectral Features of PAHs 63 2.3.5 PAH Derivatives and Related Species 64 2.3.6 Conclusions 68 2.4 The Spectroscopy of Complex Molecules 68 Holger S. P. Müller 2.4.1 Introduction 68 2.4.2 General Spectroscopic Considerations 69 2.4.3 The Quest for Interstellar Glycine 72 2.4.4 General Astronomic Considerations 73 2.4.5 Alkyl Alcohols 77 2.4.6 Alkyl Ethers 83 2.4.7 Esters 87 2.4.8 Alkyl Cyanides 89 2.4.9 Other Complex Molecules 91 References 97 3 Gas Phase Chemistry 109 Stephan Schlemmer 3.1 Introduction 109 3.1.1 Cross Sections and Rate Coefficients for Binary Collisions 117 3.1.2 Differential Scattering and Crossed Beam Experiments 123 3.1.3 Low-Energy Collisions in Merged Beams and Integral Cross Sections 128 3.1.4 Low-Temperature Collisions in Beams and Traps,Thermal Rate Coefficients 132 Acknowledgment 143 3.2 Dissociative Recombination 143 Wolf Geppert, Andreas Wolf, and Juraj Glosik 3.2.1 Principle and Main Occurrence 143 3.2.2 Methods of Laboratory Study 151 3.2.3 Recent Laboratory Results and their Impact on Molecular Astrophysics 157 3.3 Inelastic Processes 163 David Parker and Laurent Wiesenfeld 3.3.1 Introduction 163 3.3.2 Molecular Beam Measurements of Inelastic Scattering in Water 164 3.3.3 Laser Ionization of Molecular Hydrogen and NascentWater 168 3.3.4 Experimental Details 169 3.3.5 Calculating Differential and Total Cross Sections 171 3.3.6 Water–Hydrogen Molecule PES 172 3.3.7 Dynamical Calculations 174 3.3.8 Theory and Experiments Comparisons 175 3.4 Low Temperature Trapping Experiments 179 Oskar Asvany and Stephan Schlemmer 3.4.1 N+ + H2 181 3.4.2 H+3 + H2 184 3.4.3 Deuterium Fractionation 190 3.4.4 Trap Experiments on Deuterium Enrichment 195 3.4.5 Toward State-to-State Rate Coefficients 202 3.5 Negative Ion Chemistry in the Early Universe 205 Holger Kreckel and Daniel Wolf Savin 3.5.1 Introduction: Negative Ions in Space 205 3.5.2 The Chemistry of the Early Universe 206 3.5.3 H2 Formation by Associative Detachment of H− and H 208 3.5.4 H− Photodetachment 215 3.5.5 Mutual Neutralization of H− and H+ 216 3.5.6 Summary 218 Acknowledgments 219 References 219 4 Molecular Photodissociation 229 Ewine F. van Dishoeck and Ruud Visser 4.1 Introduction 229 4.2 Photodissociation Processes 230 4.2.1 Small Molecules 230 4.2.2 Large Molecules 233 4.3 Photodissociation Cross Sections 234 4.3.1 Theory 234 4.3.2 Experiments 238 4.3.3 Photodissociation Products 240 4.4 Astrophysical Radiation Fields 242 4.4.1 General Interstellar Radiation Field 242 4.4.2 Stellar Radiation Fields 243 4.4.3 Lyman α Radiation 244 4.4.4 Cosmic-Ray-Induced Photons 244 4.4.5 Dust Attenuation 245 4.4.6 Self-Shielding 246 4.5 Photodissociation Rates 246 4.6 Photodissociation of CO and its Isotopologs 247 4.7 Photostability of PAHs 249 4.8 Summary 251 Acknowledgments 251 References 252 5 Surface Science 255 Liv Hornekaer 5.1 Introduction 255 5.1.1 Surface Reactions under Interstellar Conditions 257 5.1.2 Experimental Methods 259 5.1.3 Introducing the Hot Topic Sections 261 5.1.4 Outlook 262 5.2 Molecular Hydrogen Formation on Carbonaceous Surfaces 262 Liv Hornekaer and Stephen D. Price 5.2.1 Interaction of Atomic Hydrogen with Carbonaceous Surfaces 263 5.2.2 Formation of Molecular Hydrogen on Carbonaceous Surfaces 264 5.2.3 Energy Partitioning in H2 Formation 269 5.2.4 Summary and Outlook 271 5.3 The Influence of Ice Morphology on Interstellar Chemistry 273 Martin McCoustra, Mark Collings, Francois Dulieu, Jean-Hugues Fillion, and Maria Elisabetta Palumbo 5.3.1 The Structure of Amorphous SolidWater (ASW) 273 5.3.2 Desorption of Molecular Hydrogen 276 5.3.3 Influence of the Morphology of the Ice on the Sticking of Hydrogen 278 5.3.4 Recombination Process 279 5.3.5 Energetic Balance of the H2 Reaction and its Consequences on the Morphology of Ice 281 5.3.6 The Impact of Ice Morphology on Thermal Desorption Processes for Other Small Molecules 282 5.3.7 ASW Morphology Changes due to Ion and UV Irradiation 287 5.4 Solid-State Pathways toward Molecular Complexity in Space 289 Sergio Ioppolo, Karin I. Öberg, and Harold Linnartz 5.4.1 General Information on Experimental Techniques 290 5.4.2 Atom Bombardment 292 5.4.3 O/O2/O3 + H 296 5.4.4 UV Photoprocessing 299 Acknowledgments 309 5.5 New Calculational Strategies for Including Surface Reactions in Astrochemical Network Models 309 Eric Herbst 5.5.1 Rate Equations 310 5.5.2 Stochastic Methods 313 5.5.3 Modified Rate Equations 316 5.5.4 Microscopic Studies: A Kinetic Monte Carlo Approach 316 5.5.5 Summary 318 References 319 6 Dust and Nanoparticle Spectroscopy 327 Harald Mutschke 6.1 Introduction I: Spectroscopic Observations of Cosmic Dust 327 Thomas Henning 6.1.1 Dust in the Interstellar Medium 327 6.1.2 Stardust 332 6.1.3 Dust in Planetary and Protoplanetary Systems 334 6.2 Introduction II: Techniques in Laboratory Dust Spectroscopy 337 Harald Mutschke and Akemi Tamanai 6.2.1 Calculated Versus Measured Comparison Spectra 337 6.2.2 Measuring Dust Absorption Spectra 341 6.2.3 Determination of Optical Constants of Solids 347 6.3 The Bulk of Interstellar Dust: Amorphous Silicates 350 Harald Mutschke and Simon Zeidler 6.3.1 Structure of Silicates 351 6.3.2 Production Techniques for Amorphous Silicates 354 6.3.3 The Infrared Spectra of Amorphous Silicates 356 6.3.4 Optical Constants at UV/Vis/NIRWavelengths 358 6.3.5 The Far-Infrared Emissivity of Cold Amorphous Silicates 359 6.4 Crystalline Silicates 361 Chiyoe Koike 6.4.1 The Effect of Silicate Composition on Infrared Spectra 362 6.4.2 Temperature Effects on Infrared Spectra of Olivine and Pyroxene Particles 365 6.4.3 Optical Constants of Olivine at Room Temperature and Low Temperature 366 6.4.4 Structural Defects of Silicates 368 6.4.5 Shape Effects and Medium Effects on Infrared Spectra of Forsterite 370 6.4.6 The missing Iron Content Problem 370 6.5 Oxides as High-Temperature Condensates 372 Thomas Posch and Simon Zeidler 6.5.1 The Role of Oxide Dust in the Cosmic Matter Circuit 372 6.5.2 A General Remark on the IR Bands of Refractory Oxides 373 6.5.3 Al Oxides, Ca–Al Oxides, and Mg–Al Oxides 375 6.5.4 Silicon Oxides (SiO2 and SiO) 378 6.5.5 Iron Oxides and Mg–Fe Oxides 380 6.5.6 Titanium Oxides 381 6.5.7 Constraining the Optical Constants in the NIR Region 382 6.5.8 Temperature Dependence of the Optical Constants 383 6.6 Spectroscopic Properties of Carbon Compounds 385 Harald Mutschke and Cornelia Jäger 6.6.1 Graphite, Diamond, and Fullerite 386 6.6.2 Hydrogenated Amorphous Carbon 390 6.6.3 Silicon Carbide and Other Carbides 394 6.7 Photoluminescence Studies of Silicon-Based Nanoparticles 397 Friedrich Huisken, Olivier Guillois, Olivier Debieu, Karsten Potrick, and Torsten Schmidt 6.7.1 Effects of Nanoscale Particle Size 397 6.7.2 PL Spectra of Free Si NCs 398 6.7.3 PL Spectra of Matrix-Embedded Si NCs 402 6.7.4 PL Spectra of Silicon Dioxide NPs 404 6.7.5 Consequences for the Interpretation of PL Observations 406 Acknowledgments 408 References 409 7 Formation of Nanoparticles and Solids 419 Cornelia Jäger 7.1 Condensation of Cosmic Dust in Astrophysical Environments 419 Hans-Peter Gail 7.1.1 Element Abundances in Dust-Forming Objects 420 7.1.2 AGB Stars 422 7.1.3 Massive Stars 425 7.1.4 Condensation Sequences 427 7.1.5 Principles of the Dust Formation Process 431 7.1.6 Condensation Temperature 433 7.1.7 Reaction Kinetics 435 7.1.8 Mineral Formation in M Stars 436 7.1.9 Condensation of Carbonaceous Grains in C Stars 438 7.1.10 Formation of Minerals in C Stars 445 7.1.11 Concluding Remarks 446 7.2 Laboratory Approach to Gas-Phase Condensation of Particles 447 Cornelia Jäger 7.2.1 Gas-Phase Condensation Methods in the Laboratory 447 7.2.2 Laboratory Tools for the Characterization of Condensation Products 452 7.3 Gas-phase Condensation Experiments of Magnesium Iron Silicates 455 Frans J.M. Rietmeijer and Joseph A. Nuth 7.3.1 Grain Production and Characterization 456 7.3.2 Grain Compositions 458 7.3.3 Magnesium Iron Silicates 461 7.3.4 Time Versus Temperature 464 7.4 Gas-Phase Condensation of Carbonaceous Particles in the Laboratory 467 Cornelia Jäger, Harald Mutschke 7.4.1 Condensation Pathways of Carbon Nanograins at Different Temperatures 467 7.4.2 Characterization of the Condensation Products 469 7.4.3 Formation Pathways of Carbon Grains and Astrophysical Discussion 471 7.4.4 Spectral Properties of the HT and LT Condensates 473 7.5 Processing of Silicates 477 Cornelia Jäger 7.5.1 Thermal Annealing 478 7.5.2 Ion Bombardment 480 7.6 Carbon Dust Modifications underThermal Annealing and Irradiation by UV Photons, Ions, and H Atoms 484 Vito Mennella 7.6.1 Thermal Annealing 485 7.6.2 UV Irradiation 486 7.6.3 Ion Bombardment 488 7.6.4 H-Atom Irradiation 490 7.6.5 Conclusions 493 Acknowledgments 493 References 493 Index 501

About the Author :
Stephan Schlemmer is the head of the laboratory astrophysics group at the University of Cologne. He received his PhD from Georg August University, Göttingen and was awarded the Otto-Hahn medal of the Max-Planck Society. He spent two years as postdoc at UC Berkeley. At Chemnitz University of Technology he worked as an assistant professor. He was appointed at the Leiden observatory as an associate professor before moving to Cologne. He has authored more than 50 scientific publications specializing in spectroscopy and dynamics of molecular physics. Harald Mutschke is the head of the laboratory astrophysics group at the Friedrich-Schiller-University Jena where he obtained his PhD in solid state physics. He has authored more than 90 scientific publications on spectroscopy of small solid particles with relevance for cosmic dust. Thomas Giesen is a research assistant at the university of Cologne. He received his PhD in physics at the University of Cologne and spent 18 months as a postdoctoral research fellow of the Max Kade foundation at the University of Berkeley. His main research activities comprise reactive carbon containing molecules and radicals, produced in laser ablation and electrical discharge sources. T. Giesen is author and co-author of more than 40 publications in refereed journals. His publication on carbon chain molecules has been awarded the Sir Harold Thomson Memorial award 2003.