Lorentz Center - Solid State Chemistry in Star Forming Regions organised on behalf of the Astrophysical Chemistry Group of the Royal Society of Chemistry and Royal Astronomical Society
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    Solid State Chemistry in Star Forming Regions
    organised on behalf of the Astrophysical Chemistry Group of the Royal Society of Chemistry and Royal Astronomical Society

Invited Lectures – Abstracts

Invited Lectures – Abstracts


DAY 1 – Data Needs and Requirements from Modelling Perspectives


Heterogeneous Chemistry in Astronomy: Data Needs and Requirements

Ewine van Dishoeck

In this introductory lecture, a broad overview will be given of gases and solid state matter found in star-forming regions. The techniques used by astronomers to detect the various species will be presented and the methods used to deduce qualitative (e.g., identification, environment) and quantitative (e.g., abundances, physical conditions)
information will be summarized. The needs and requirements for laboratory data will be emphasized, and illustrated with recent examples.



Inside a Typical Astrochemical Model

Serena Viti


In this lecture, I will provide a 'tour' inside a typical astrochemical model, underlining some of their complexities and weaknesses.  With this 'tour', I hope to show how complex models are essential in order to represent the chemical and dynamical behaviour of astronomical objects.  The main complexity in running astrochemical models arises in the physical situation in which the chemistry is assumed to operate since, usually, at least some of the physical parameters are time and space dependent; this requires the chemistry to be determined as a function of space and time.  This is just one of reasons why astrochemistry has created a huge demand for both theoretical and experimental fundamental data; as a consequence, a key feature of astrochemistry is its interdisciplinary nature and this will highlighted during the talk.


Some Problems and Limitations of Astrochemical Models

Jonathan Rawlings


Astrochemical modelling has enjoyed some notable successes for a wide range of astrophysical environments; for example in matching the observed abundances of (most) molecular species within dark clouds, such as TMC1. There are, of course, some well-known `failures'; such as the still unresolved `CH+ problem', and the relatively weak comprehension of the molecular processes within diffuse clouds. But - bearing in mind the uncertainties in the chemical networks and the simplicity of the models - considerable successes are often achieved.

However, when one tries to use these models to make diagnostic predictions, it is  often found that they are limited by the implicit simplifications and assumptions. Thus, the role of surface chemistry and depletions of key elements are often unknown, as are the physical constraints on the modelled sources;- the temperature/density structure and, perhaps most importantly, the kinematics. Moreover, kinetic models need to have a clearly defined set of initial conditions. The nature and implications of these uncertainties are discussed.


Data, Data Everywhere! But which of it to use?

The Need for Data Validation and Accountability in Laboratory Astrochemistry

Martin McCoustra


There is no doubt that modern astronomy and astrophysics need laboratory data. Laboratory spectra provide a means of confirming observational assignments, while chemical rate data are crucial to modelling the chemical evolution of the interstellar medium. In this respect, there is much in common with atmospheric science in that this discipline also seeks to couple chemistry and physics in understanding complex problems. This presentation will use this comparison to argue that by adopting, at an international level, a policy of data co-ordination and validation beyond that represented by the likes of the Leiden spectral and UMIST kinetics databases, users of our data can then focus more closely on the physics of their particular problems with an assurance that the quality of the chemical data they might incorporate into their models is without question.


DAY 2 – H2 Formation and Destruction


The Formation and Destruction of Hydrogen Molecules in Astrophysical Environments

Alex Dalgarno


The chemical processes that were effective in forming and destroying molecular hydrogen in the recombination era of the early Universe, in gravitationally collapsing clouds, in shocked regions of the interstellar gas and in cold interstellar clouds, are reviewed. A discussion is presented of the astrophysical evidence on the efficiency of the formation of H2 and the distribution of its recombination energy between rotation, vibration and translation.


H2 Formation on Astronomically Relevant Surfaces

V. Pirronello** (in association with G. Manico' , J. Roser , G. Vidali)


In this talk results will be presented of recent measurements of the formation of molecular hydrogen taking place on the three main classes of astrophysically relevant (carbonaceous, silicate and icy) surfaces in conditions close to those encountered in interstellar clouds. Attention will be paid to the mechanisms that might be responsible

for the occurrence of the processes leading to the recombination events. Astrophysical consequences of the experimental results together with possible future investigations will also be outlined.


H2 Formation on Amorphous Solid Water (ASW): New Experiments and a New Interpretation

A. C. Luntz**  and Liv Hornekaer**, (in association with A. Baurichter and V. Petrunin)


Laboratory studies of H2 formation on a number of different surfaces of interstellar relevance have been pioneered by Vidali, Pirronello and co-workers. Using similar experimental techniques to those of Vidali, et. al.,  we present new and extensive experiments for H2 formation on various forms of amorphous solid water surfaces. These results are in only partial agreement with those reported by Roser, et. al. and suggest a very different formation mechanism to the one discussed by them. We believe our experiments (and mechanism) are in qualitative accord with what is known of ASW structures and well accepted surface science concepts and prior studies.  


H2 Formation in Vibrationally Excited States: Laboratory Results

Stephen Price


We will discuss the first results from an experimental programme which measures the ro-vibrational distribution of molecular hydrogen formed, by recombination of a controlled beam of atomic hydrogen, on cold prototypical interstellar surfaces under ultra-high vacuum conditions. These laser spectroscopic results show that vibrationally excited hydrogen molecules, n = 1 and n = 2, are certainly formed in such heterogeneous processes. These excited vibrational levels possess moderate rotational excitation. The strengths, and weaknesses, of this experimental approach will be discussed, as well as the prospects for further application of such laser spectroscopic techniques to determine the energy budget for a variety of heterogeneous processes implicated in interstellar molecular synthesis.


Quantum Dynamical Calculations on the Surface Catalysed Formation of H2 in Interstellar Space.

Anthony J. H. M. Meijer


H2 is one of the most important molecules in the interstellar medium. It plays a pivotal role in interstellar chemistry through reactions with ions and radicals. It is widely accepted that the dominant mechanism for the formation of H2 in interstellar clouds is through surface-catalysed reactions on dust-grains.

H(g) + H(ads) = graphite ®  H2(n; j) + graphite

In this talk I will give an overview of current quantum theoretical calculations on this system. I will also present the results of some recent wave packet studies on this reaction.


The Effects of Including H2 Laboratory and Theoretical Data into “Formation Pumping” Models and Spectra

Junko Takahashi


We have developed our “formation pumping” models for H2 formation in astronomical environments, such as icy mantles, silicate dust and carbonaceous dust, on the basis of the recent laboratory and theoretical data that has been published on surface mediated H2 formation.  Then, we calculated the H2 emission spectra arising from formation pumping, considering one region in the early stages of evolution from H I to H2 clouds.  The resulting infrared H2 emission spectra can be used as a new probe that not only discriminates from those spectra dominated by UV pumping but also holds information about the dust properties.


DAY 3 – Ice Formation, Structure and Spectroscopy


Laboratory Studies of Nanoscale Films of Amorphous Solid Water

Bruce D. Kay**, (in association with Patrick Ayotte, John L. Daschbach, Zdenek Dohnálek, Greg A. Kimmel, R. Scott Smith, Kip P. Stevenson, and Glenn Teeter)


Molecular beam scattering, programmed desorption (both TPD and isothermal), optical interference, and vibrational spectroscopy are used to study the chemical kinetics and reaction dynamics of molecular processes occurring both on the surface and within the bulk of amorphous and crystalline ice films. Molecular beams are used to synthesize chemically and structurally tailored thin films. These films can have morphologies ranging from dense and smooth, to highly porous depending on growth conditions. The precise control of the film structure allows physiochemical processes such as densification, crystallization and solvation to be studied in detail. The experimental methods, results, and their relevance to astrophysical icy bodies, nanoporous materials, supercooled water, and aqueous solutions will be presented. 


Formation, Energetic Processing, and Destruction of Ices in Star Forming Regions

Louis d’Hendecourt and Emmanuel Dartois


The presence of physisorbed ices covering the refractory interstellar grains in dense regions was detected more than two decades ago. In the past years, medium resolution spectroscopic surveys in the infrared of the circumstellar dust around young stellar objects have allowed us to follow the chemical evolution of solid matter surrounding embedded young stellar objects (YSOs). I will present an introduction to the observation of these ices and briefly discuss the various energetic sources of astrophysical importance that can lead to their formation (UV, proton irradiation, surface reactions). Besides the grain mantles composition inventory obtained by comparing the solid state features with laboratory data, the analysis of band profiles can trace and highlight the solid structure and molecular interactions taking place in the mantles. I will present two studies of these profiles: the formation of an interstellar intermolecular complex CO2-CH3OH , and the formation of an ammonia hydrate. Finally I will present some aspects of the possible evolution of this organic matter in the laboratory.  I will in particular discuss the possibility to follow in the laboratory the organic matter evolution from the elementary molecules found in protostellar environments to the more complex molecules incorporated in protoplanetary systems.


Understanding Interstellar Ices: Physical Processes and their Effects on Chemical Properties

 M. E. Palumbo


At the Catania Laboratory of Experimental Astrophysics, we have been studying, by infrared and Raman spectroscopy, the effects induced by fast ions impinging on astrophysical relevant solids. Among other effects, ion irradiation of ices, causes the formation of molecular species not present in the original sample as well as structural modifications of the target. Furthermore a refractory residue is left over after warm up to room temperature. Recently we have added a Lyman-alpha lamp to our experimental set-up. This gives us the capability to study and compare the effects induced in frozen gases by ions and UV photons. Here I will present some experimental results and discuss their astrophysical relevance.


Experimental and Quantum Investigations on Amorphous Ice Surface Structure and Reactivity



The amorphous ice mantle on interstellar grains plays a major role in the formation of astrophysical molecular species. Here I will discuss laboratory experiments based on FT-IR and coupled FT-IR/volumetric methods, at temperatures ranging from 7 to 100K, which provide information about the surface structure of amorphous ice via non-polar non-hydrophylic molecular adsorption. The structure of the ice, in turn, influences the chemical reactivity. On amorphous ice, the water molecules can act either as catalysts or as reactive participants.

Quantum modeling give more precise detail on  the role of the strong electric fields existing in ice and also the cooperative effects of the hydrogen bond network responsible for the solid cohesion. Due to this last phenomenon, the ice surface reactivity develops a special kind of chemistry, characterized by low energy barriers through which electrons and protons can easily tunnel.


Ices in Star-forming Regions

Xander Thielens


Ground-based, air-borne and space-based, infrared spectra of protostars show prominent absorption features at 3.08, 3.54, 4.23, 4.38, 4.67, 4.9, 6.0, 6.85, 7.6 and 15.2 microns.  These features are due to simple molecules such as H2O, CH3OH, CO2, CO, OCS, and CH4 in accreted icy grain mantles.

These studies have revealed the presence of several independent ice components, often along the same line of sight.  The observations and proposed identifications will be reviewed with the emphasis on recent results from ISO and on the organic inventory of interstellar ices. These molecular grain mantles are thought to form by accretion and reaction of gas phase species on a grain surface.  Important grain surface routes will be delineated.  Besides grain surface chemistry, the evolution of interstellar ices can also be driven by thermal processing by nearby newly formed protostars, leading to the formation of a so-called Hot Core region with a gas phase composition dominated by simple hydrogenated species.  An active chemistry takes place in these warm (>100 K), dense (>10^6 cm-3) regions driven largely by the release of alcohols.  The gas phase composition of such regions provides another

window on the composition of interstellar ice mantles formed during preceding dark and cold phases.  Interstellar ices can also be processed by FUV photons.  This photolysis may lead to the formation of a complex residue, but the importance of this route is not well established.  Finally, various links to the solar system will be pointed out.





DAY 4 – Surface Reactions and Interactions

Observations of Gas-Grain Chemistry in Star Forming Regions

Ted Bergin


I will present the observational evidence for grain surface chemistry of both simple and complex molecules in star forming regions.  This will include a discussion regarding the observational uncertainties in molecular identification, interpretation, and on deriving chemical abundances. 


Photo Physics And Photo Chemistry Of Ice Films On Graphite

Dinko Chakarov


The extensive interest in the physics and chemistry of ice is motivated by its universal appearance; in particular by the special role of ice films in ozone depletion chemistry, cometary science, and astrophysics. In these examples, the structure of ice and its chemical properties are strongly influenced and altered by incoming photons. Our model system consists of thin films with sub-monolayer to several monolayers thickness deposited at ultrahigh vacuum and low (from ~25 K) temperatures on atomically clean graphite (0001) surface. The films are characterized before, during, and after cw or pulsed photon irradiation in broad wavelength and photon flux ranges with temperature programmed desorption - isothermal desorption spectroscopy (TPD - ITD) and high-resolution electron energy loss spectroscopy (HREELS). We will discuss the phenomena of “photon annealing” of pure amorphous films and their structure-selective laser ablation: A new non-thermal mechanism by which sub-monolayer and multilayer pure amorphous ice films, deposited at T <100 K on graphite surface, crystallize due to UV radiation. In the case of ice doped with alkali metals, we will report on the observations of photoreactions induced on graphite (0001) surface covered with thin ice film at 90 K. Introduction of sub-monolayer amounts of alkali atoms to the system leads to photodesorption of H2, CH4, CO, and CO2 . In both cases the operating mechanism is associated with photo excited charge carriers in the graphite substrate.


Adsorption and Reactions of Simple Molecules at Grain and Ice Surfaces

Helen Fraser** and Klaus Pontoppidan**


It is now widely accepted that surface chemistry and physical processes play a significant role in the chemical evolution of dense molecular clouds and collapsing protostellar cores. The synergy between gas and dust grains is being explored in laboratory, observational and theoretical Astrochemistry. For molecular species that are thought to form predominantly in the gas phase, such as CO, it is generally assumed that they remain in this state until 'freezing-out' at or below their sublimation temperature, into solid molecular ices. However, analysis of recent observations of over 25 young stellar objects challenges this simple picture, and together with laboratory evidence, suggests that gas-surface interactions, and the role of gas adsorbates in processes at grain surfaces, might also be important reaction pathways to molecular formation in dense molecular clouds and protostellar regions, which have so far been overlooked. The chemical and physical processing of ices and gas adsorbate systems formed this way will be discussed, focusing particularly on CO containing ices and chemical pathways involving CO.


Hydrogen Reactions On Ice/ Grain Surfaces

Kenzo Hiraoka


The reaction of H with solid CO led to the formation of HCHO but no CH3OH could be detected. The rates of the tunnelling reactions show steep increase with decrease of temperature and reach a maximum at about 13K for C2H4, C6H6 and C6H10. This suggests the existence of resonance states for the reactions. Some theoretical considerations will also be given.


Sticking Of HCl, CO, And H To Ice: Classical Trajectory Results For Systems Of Astrophysical And Atmospheric Interest.

G.J. Kroes


Classical trajectory results will be presented on the sticking of HCl, CO and H to the basal plane (0001) face of crystalline ice Ih. The calculations are based on appropriate pair potentials for the X-H2O interactions (X=HCl, CO, and H), and on the TIP4P pair potential for interactions between water molecules.

A surprising result for HCl + ice is that HCl can penetrate the surface of ice at energies (≈ 1 eV) which are at least an order of magnitude lower than energies at which penetration of metal and semi-conductor surfaces by rare gas atoms becomes possible. The penetration shows a significant dependence on the initial orientation of HCl: non-rotating (j=0) HCl is more than 50% more likely to penetrate the surface with its Cl-end initially pointing down to the surface than with its H-end pointing down.

In contrast to HCl, CO does not penetrate the surface of ice at a collision energy of about 1 eV. The type of collisions that lead to penetration for HCl lead to surface damage for CO. Energy minimizations suggest that CO is adsorbed either on top of a dangling OH-group, or on top of the centre of a water hexagonal ring, interacting mostly with an electron lone-pair oxygen atom in the first or second monolayer. The dynamics calculations suggest an average binding energy of 4.3 and a maximum binding energy of 10.4 kJ/mole for CO + ice [4].

At low collision energies (100-600 K), the sticking probability of H on ice shows a monotonic decay with the collision energy. In the adsorbed state, the H-atom is located over the centre of a hexagonal ring, with an adsorption energy of 400 ± 50 K. Our adsorption probabilities are higher than those calculated by Buch and Zhang for amorphous ice, which was attributed to differences in surface morphology. On the other hand, our calculated adsorption probabilities are lower than those calculated by Masuda et al. for amorphous ice, which we attribute to an incorrect implementation of the H-H2O potential in their work.


Which Reactions Are KEY To Astronomical Models?

S.B. Charnley


I will discuss which reactions are key to astronomical models.

Poster Titles


Ion Irradiation And UV Photolysis Of Astrophysical Relevant Solids

G. A. Baratta, G. Leto, M. E. Palumbo, F. Spinella, G. Strazzulla

INAF, Osservatorio Astrofisico di Catania, I-95123 Catania, Italy


Diffusion Of Hydrogen On Cosmic Dust Grains

Adam J Farebrother, Anthony J.H.M. Meijer and David C Clary.

Department of Chemistry, University College, London, UK


Sticking Of CO To Amorphous And Crystalline Ice

A. Al-Halabi, G. J. Kroes

Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Einsteinweg 55 / P.O. Box 9502 2300RA, Leiden, The Netherlands.


Studies Of Astronomically Important Addition Reactions On  Dust Grain Analogue Surfaces.

A. Bolina*, W.Brown

UCL, London, UK

* Recipient of Young Researcher Bursary


Laboratory Studies of Ion, Photon and Electron Irradiated Astrophysical Ice Analogues

M. P. Davis1, A. Dawes2, S. V. Hoffmann3, P. Holtom2, N. J. Mason1,2, R. W. McCullough4, I. D. Williams4

1Department of Physics and Astronomy, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK

2Department of Physics and Astronomy, University College London, Gower Street, WC1E 6BT, UK

3Institute for Storage Ring Facilities, University of Aarhus, Ny Munkegade, bygn. 520, DK-8000 Aarhus C, Denmark

4Atomic and Molecular Physics Research Div., The Queen's University of Belfast, Belfast BT7 1NN, N. Ireland, UK


Simulation Of Interstellar Grain Surface Chemistry And Reaction Dynamics: The Odense Facility

A. Baurichter*, L. Hornekaer*, V.V.Petrunin, D. Field1, A.C. Luntz

Physics Dept., University of Southern Denmark, Odense, Denmark

1Institute for Physics and Astronomy, Aarhus University, Aarhus, Denmark

* Recipient of Young Researcher Bursary


Theory Of H Atom Chemisorption And Recombination On Graphite Surfaces

B. Jackson

Department of Chemistry, 701A LGRT,  University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003-9336, USA


Ro-Vibrational Excitation Of Hydrogen Formed By Association In A Very Intense Expanding Plasma.

D.C.Schram, P.Vankan, S.Heil, R.Engeln

Eindhoven University of Technologie, Department of Applied Physics, Eindhoeven, The Netherlands


Synthesis Of Ammonia From Highly Dissociated Hydrogen And Nitrogen Plasma Jets In Plasma Surface Interactions.

D.C.Schram, J. van Helden, P. Vankan, R.Engeln

Eindhoven University of Technologie, Department of Applied Physics, Eindhoeven, The Netherlands


Observations Of Gas-Grain Chemistry In Star-Forming Regions

F. van der Tak*

MPI, Bonn, Germany

* Recipient of Young Researcher Bursary


Tracing Complex Volatiles from Space

F.A. van Broekhuizen1, H.J. Fraser1, W.A. Schutte1, E. de Kuijper2 & E.F. van Dishoeck1

1 Sackler laboratory and Sterrewacht Leiden, University of Leiden, The Netherlands,

2 F.M.D., University of Leiden, The Netherlands


Experimental Studies of Formation of Molecules on Dust Grain Analogues under ISM Conditions

Gianfranco Vidali1, Joe Roser1, Robert d'Agostino1, Valerio Pirronello2 and Giulio Manico2

1Syracuse University, Syracuse, NY 13244 USA

2Universita' di Catania, Catania, Italy)


Quantum State Resolved Gas-Surface Interactions

Greg O. Sitz

 The Physics Department, The University of Texas at Austin, USA.


Experimental Light Scattering By Astronomical Dust

Hester Volten

AMOLF, Amsterdam, The Netherlands


Chemical and Physical Structures of Massive Star Forming Regions

Hideko Nomura

Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, UK


Two-dimensional Models of Protoplanetary Disk Chemistry?

Hideko Nomura

Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, UK


Rate Coefficients for Astrochemistry

Ian Sims

School of Chemical Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom


A Novel Instrument To Probe H2 Formation On The Surface Of Interstellar Grain Analogues.

Jean Louis Lemaire

UMR 8112 du CNRS, Universite de Cergy-Pontoise, LERMA-LAMAp 95031, Cergy-Pontoise Cedex, France

and Observatoire de Paris-Meudon  LERMA 92195 Meudon Cedex, France


The Physical Properties Of The Star Forming Region N88A And Its Neighbourhood In The SMC.

Jean Louis Lemaire

UMR 8112 du CNRS, Universite de Cergy-Pontoise, LERMA-LAMAp 95031, Cergy-Pontoise Cedex, France

and Observatoire de Paris-Meudon  LERMA 92195 Meudon Cedex, France


Ultrahigh Vacuum Studies of Interstellar Ice Morphology - an overview of research in the Nottingham Surface Astrophysics Experiment

Mark Collings*

School of Chemistry, University of Nottingham, Nottingham, UK

* Recipient of Young Researcher Bursary

Infalling And Rotating Pre-Stellar Cores

Matt Redman*

Department of Astronomy, UCL, UK

* Recipient of Young Researcher Bursary


Interaction Of Small Organic Molecules With The Surfaces Of Amorphous And Crystalline Ice

Mihail Grecea, Ellen Backus, Aart Kleyn and Mischa Bonn

University of Leiden, Leiden Institute of Chemistry, Gorlaeus Laboratory, P.O. Box 9502, NL-2300 RA Leiden, The Netherlands


Proton Sticking On Crystalline Ice

P.Cabrera Sanfelix1, S. Holloway1, K.W. Kolasinski2, G.J.Kroes3, A. Al-Halabi3 and G.R. Darling1

1Surface Science Research Centre, Department of Chemistry, The University of Liverpool L69 3BX, UK

2Department of Chemistry, Queen Mary, University of London, Mile End Road, London E1 4NS, UK

3Gorlaeus Laboratories, Leiden Institute of Chemistry, P.O.Box 9502, 2300 RA Leiden, The Netherlands


Absolute Infrared Absorption Intensities - a.k.a. 'Band strengths': Laboratory Measurements and their Implications for Solid-State Astrochemistry

Perry A. Gerakines

Astro- and Solar-System Physics Program, Department of Physics, University of Alabama at Birmingham, Birmingham, AL USA


Solid-Phase Formation of Interstellar Vinyl Alcohol

R. L. Hudson1,2 and Marla H. Moore2

1Eckerd College, USA

2NASA Goddard, USA


Simulation Of The H+CO Reaction On Ice Surfaces

Stefan Andersson

Leiden Observatory, P.O. Box 9513, 2300 RA Leiden, The Netherlands


Interaction Of Electrons And Molecules With A Single Trapped Nanoparticle

S. Schlemmer, S. Wellert, F. Windisch, M. Grimm, S. Barth and D. Gerlich

Faculty of Natural Science, University of Technology, 09107 Chemnitz, Germany


Experiments To Measure The Ro-Vibrational Distribution Of H2 Formed On Cosmic Dust Analogues

Susan Creighan*, Stephen Price

Department of Chemistry, UCL, UK

* Recipient of Young Researcher Bursary


Direct Master Equation Approach to Modeling the Chemistry on Interstellar Grains

T. Stantcheva*, V. Shematovich, and E. Herbst

Ohio State University, Columbus, OH, U.S.A.


OCN- Formation From Reactions Involving HNCO In The Interstellar Medium Conditions

S. Raunier, T. Chiavassa*, F. Marinelli, A. Allouche, J.P. Aycard.

Universite de Provence et CNRS, Centre de St Jerome, case 252 13397 MARSEILLE cedex 20, France

* Recipient of Young Researcher Bursary


Adsorption And Recombination Via Abstraction Of H(D)On Graphite(0001) Surfaces

Thomas Zecho* and Juergen Kueppers

University of Bayreuth, Germany

* Recipient of Young Researcher Bursary


The Physical Behaviour of CO on, in, and under, interstellar ice analogues


W.Alsindi, S.Bisschop* and H.J.Fraser


Raymond and Beverly Sackler Laboratory for Astrophysics, Leiden

Observatory, Netherlands

* Current Address: Department of Geology and Space Sceinces, CalTech, LA,



Reactions with HD in a low temperature 22-pole ion trap

O. Asvany, S.  Schlemmer and D. Gerlich

TU Chemnitz, Germany


Absence of surface crystallization of amorphous ice
 Ellen Backus, Mihail Grecea, Aart Kleyn and Mischa Bonn

Leiden Institute of Chemistry, Leiden University, Netherlands