of caged molecules
Water is one of the most intriguing substances in the universe. It
exists almost everywhere from interstellar space to the depth of our
oceans. They exhibit interesting physical and chemical properties.
Over solid surfaces water grows as Amorphous Solid Water (ASW),
having unique properties that we plan to explore.
One interesting feature is the caging phenomenon. If we adsorb
molecules upon a surface and then further adsorb water molecules,
the later will substitute the parent molecules at the binding sites
on the surface. If the amount of water molecules is large enough
(coverage > 10ML) the parent molecules will be concentrated as a
micelle-like cage at a point inside the bulk of the thin ASW
film. Photochemistry of caged molecules displays different chemical
and physical properties than surface photochemistry. The model that
describes these reactions is the Dissociative Electron Attachment (DEA).
Usually, the substrate-electrons are pumped onto the adsorbent, in
the case of ASW; the later stabilizes these hot electrons.
ASW has the ability, not only to stabilize photo induced electrons,
but also positive ions. If the ion deposition takes place on the ASW-vacuum
interface a capacitor-like thin film is produced: A nano-capacitor.
The inner electric field that develops is of high magnitude due to
the small distance between the substrate acting as the first
electrode and the surface of the ASW, acting as the counter
In this research I shall investigate the photochemistry of trapped,
caged molecules initiated by hot electrons under the influence of
electric field induced by the charged ASW nano-capacitor. Charging
the dielectric material from dipolar (water or ammonia) to non-polar
(e.g. hexane) novel properties of such nano-capacitor will be
explored. In addition, upon embedding semi conducting or metallic
films (or quantum dots) within the ASW nano-capacitor new
photochemical pathways will be revealed.