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Dependencia de la velocidad inversa de la emisión de electrones promovida vibracionalmente desde una superficie
N H Nahler1, J D White, J Larue
1Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106-9510, USA.
Science (New York, N.Y.)
|August 30, 2008
Resumen
La probabilidad de emisión de electrones aumenta a medida que disminuye la velocidad de la molécula durante las colisiones superficiales. Esto contradice los hallazgos anteriores y sugiere un nuevo mecanismo de desprendimiento automático vibratorio que influye en las reacciones superficiales.
Área de la Ciencia:
- Ciencias de la superficie Ciencias de la superficie.
- Química física es la química física de las cosas.
- Física Química Física Química es el campo de la física química.
Sus antecedentes:
- Los efectos electrónicos no adiabáticos suelen aumentar con la velocidad molecular en las superficies metálicas.
- Los modelos teóricos existentes no capturan completamente todos los fenómenos de interacción de superficie observados.
Objetivo del estudio:
- Para investigar la dependencia de la velocidad de los efectos electrónicos no adiabáticos durante las colisiones moleculares con una superficie metálica.
- Para explorar los mecanismos de emisión de electrones de una superficie de oro cubierta de cesio con moléculas de óxido nítrico altamente excitadas por vibración.
Principales métodos:
- Observación experimental de la emisión de electrones durante las colisiones de moléculas de óxido nítrico (NO) con una superficie dorada cubierta de cesio (Au111/Cs).
- Variación de la velocidad incidente de las moléculas de NO, centrándose específicamente en los estados altamente excitados vibracionalmente (V = 18).
Principales resultados:
- Se observó un efecto electrónico no adiabático en el que la probabilidad de emisión de electrones aumenta a medida que disminuye la velocidad de la molécula de NO incidente.
- La probabilidad de emisión de electrones alcanzó 0,1 a las velocidades más bajas estudiadas.
- Los resultados son consistentes con un mecanismo de separación automática vibratoria que requiere una distancia crítica de la superficie.
Conclusiones:
- El estudio revela una nueva tendencia en los efectos electrónicos no adiabáticos, contrariamente a la comprensión establecida.
- Se propone un mecanismo de desprendimiento automático vibratorio para explicar la emisión de electrones observada.
- Estos hallazgos ponen de relieve las vías de disipación de energía que actualmente no se tienen en cuenta por los métodos teóricos, lo que afecta la comprensión de la velocidad de reacción de la superficie.
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