Official Launch of ALI-1000
BihurCrystal’s first deposition system — the ALI-1000 — has finally been launched this month. ALI stands for Atomic Layer Injection, and is a versatile tool for depositing molecules and nanoparticles from solution in UHV. ALI is especially useful for large or delicate molecules (including biomolecules) that degrade when heated, and can therefore not be deposited by evaporation.
The ALI Deposition System (displayed on the left) is made up of a pulse valve, used to inject the liquid into the UHV chamber, and a pre-injection system through which the liquid is introduced along with the carrier gas that is also necessary for injection. When the solution is injected into the UHV chamber, it forms a spray of microdroplets. The solvent evaporates as the droplets travel towards the sample, until finally, the solute is deposited on it.
The ALI Software and Control Unit Package provides the user with an easy-to-use graphical interface through which the injection parameters can be controlled and monitored. Importantly, it also incorporates safety features to avoid long periods of high pressure in the vacuum chamber that could cause overload in the pumping system.
One of the first experiments carried out as proof of concept for the ALI system was the deposition of Adenosine triphosphate (ATP, shown below) in UHV. ATP is a nucleoside considered to be the molecular unit of energy currency within the cell. Deposition of ATP by conventional techniques has proven to be a challenge due to the fact that the molecule easily degrades when heated. ALI overcomes this difficulty with its injection from solution. The following STM images, obtained after successful deposition with ALI, show ATP islands on a Cu(110) surface, courtesy of J. Sobrado, Centro de Astrobiología (CSIC-INTA).