Giuseppe Raguní (1965), consiguió el “Dottorato di Ricerca” realizado en las Universidades de Catania y Syracuse (EE.UU) con una tesis sobre la síntesis molecular en el medio interestelar. Ha ejercido actividad docente en Bolonia, Catania, Ravenna y Madrid. En la actualidad es Profesor Adjunto de las asignaturas de Fundamentos Físicos de Arquitectura Técnica y fundamentos Físicos de las Instalaciones en la Universidad Católica San Antonio.

LABORATORY SYNTHESIS OF MOLECULAR HYDROGEN ON WATER ICE SURFACES IN CONDITIONS OF ASTROPHYSICAL RELEVANCE

The mysterious presence of many and occasionally compllex molecular species in the interstellar clouds -ambient where cosmic rays or UV radiation should destroy them rapidly - has been explicated since the 60's with the intervention of cosmic dust grains as catalysts of chemical reactione. However, experimental facts into this explanation must wait until 1996, because the difficulties to recreate the astrophysical conditions in a laboratory. This book describes an experiment about formation of H2 -the most abundant an importat molecule in the Universe- on an iced surface in a physical environmet close to the dense coulds. The results verify the theories althought, as sometimes happens, with some discoveries.

 INDEX

1. THE INTERESTELLAR MÉDIUM

1. General overview
2. Interestellar clouds
3. Thermal balance
   1. Cooling mechanism
   2. Heating mechanism
4. Molecules in diffuse and dense clouds
5. H2 synthesis in gas phase
6. Dust grains

2. H2 SYNTHESIS ON INTERESTELLAR DUST GRAINS SURFACE

1. General
2. Principal models and theoretical calculations
3. Experiments developed until 1996
4. Measerments from astrochemical laboratory of Syracuse
5. Thermal desorption
6. Synthesis of molecular hydrogen on water ice

3. SUPERFICIAL PROCESSES OF ABSORTION, MOLECULAR SYNTHESIS AND DESORTION

1. General schemes
2. Biaham’s conservative equations
3. Stationary desorption
4. Kinetic of absorption. Lagmjuir’s law

4. EXPERIMENTAL APPARATUS

1. Introduction
2. General scheme
3. Beam sources and lines
4. Main chamber
   1. Sample holder
5. Collection of the signals
6. Other elements

5. EXPERIMENTAL PROCEDURES

1. Atomic beams calibration
2. Steps of a typical measurement procedure
   1. Degassing of sample and sample holder
   2. Cooling of the sample and beams
   3. Loading of the water line
   4. Sample degassing and re-cooling
   5. Water deposition
   6. “Dry rum”
   7. Atomic exposure
   8. Thermal posgrammed desorption and re-cooling
3. Ice density effect on HD production
4. Measurements of H2 thermal desorption

6. DATA INTERPRETACION AND CONCLUSIONES

1. Conclusions about the E.R. recombination and the first peak of the thermal desorption of HD
2. Second peak of the HD thermal desorption
3. Calculation of the activation energy for the TPD second-order desorption
4. Calculation of the net hydrogen recombination efficiency
5. Final conclusions and astrophysical implications