Video Experimental Relacionado
Updated: Jul 6, 2026
08:48
Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment
Published on: November 9, 2015
Protones chocando con hielo cristalino: reflexión de protones y desorción de agua inducida por la colisión a energías
Pepa Cabrera Sanfelix1, Ayman Al-Halabi, George R Darling
1Surface Science Research Centre, Department of Chemistry, The University of Liverpool, Liverpool L69 3BX, UK.
Journal of the American Chemical Society
|March 18, 2005
Resumen
Los protones se reflejan sorprendentemente en el hielo a bajas energías debido a la repulsión electrostática, pero se adhieren y forman complejos de Zundel a energías más altas, causando la desorción de moléculas de agua.
Área de la Ciencia:
- Química Física es la química física.
- Ciencias de la superficie Ciencias de la superficie.
- Física computacional es la física computacional.
Sus antecedentes:
- La comprensión de las interacciones de iones-superficie es crucial para campos como la astroquímica y la física del plasma.
- El comportamiento de los protones que interactúan con las superficies de hielo no se entiende completamente, particularmente a bajas energías.
Objetivo del estudio:
- Para investigar la dinámica de adherencia de los protones en el plano basal del hielo cristalino.
- Para determinar la probabilidad de adherirse, la energía de unión y los mecanismos de interacción en un rango de energías de incidencia.
Principales métodos:
- Se emplearon cálculos de trayectoria clásica (TC).
- Las simulaciones cubrieron las energías de incidencia de protones de 0.05 a 4.0 eV.
- La temperatura de la superficie se mantuvo en 80 K para la incidencia normal.
Principales resultados:
- Se observó una reflexión de protones significativa en energías de incidencia por debajo de 0,2 eV debido a las fuerzas electrostáticas repulsivas.
- La probabilidad de adherirse aumenta con la energía, alcanzando la unidad para energías mayores o iguales a 0.8 eV.
- Los protones forman complejos de Zundel (H5O2+) con una energía de unión promedio de 9.9 eV.
- Se produce la implantación de protones en la superficie del hielo, con una profundidad de penetración que aumenta con la energía.
- Se observó desorción inducida por colisión de las moléculas de agua ("puffing"), con una probabilidad que aumenta con la energía.
Conclusiones:
- Las interacciones protón-hielo son complejas, exhiben reflexión y adherencia dependientes de la energía.
- La formación de complejos de Zundel y la subsiguiente desorción de agua son resultados clave del impacto de protones.
- Estos hallazgos proporcionan información sobre los procesos superficiales relevantes para los cuerpos helados y los entornos de plasma.
Videos de Conceptos Relacionados
01:23States of Water
Water exists in any one of the three classical states: solid (ice), liquid (water), and gas (steam or water vapor). The state of water depends on i) the intermolecular forces that draw molecules together and ii) the kinetic energy that leads to movements that pull them apart.
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
Water freezes when the intermolecular forces are greater than the kinetic energy. Unlike most other substances, water is less dense in its solid state than in its liquid state. This is because each water molecule can form...
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
02:33Phase Transitions: Sublimation and Deposition
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
02:54Molecular and Ionic Solids
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
02:28Intermolecular Forces in Solutions
The formation of a solution is an example of a spontaneous process, a process that occurs under specified conditions without energy from some external source.
When the strengths of the intermolecular forces of attraction between solute and solvent species in a solution are no different than those present in the separated components, the solution is formed with no accompanying energy change. Such a solution is called an ideal solution. A mixture of ideal gases (or gases such as helium and argon,...
When the strengths of the intermolecular forces of attraction between solute and solvent species in a solution are no different than those present in the separated components, the solution is formed with no accompanying energy change. Such a solution is called an ideal solution. A mixture of ideal gases (or gases such as helium and argon,...
01:10Recrystallization: Solid–Solution Equilibria
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...