from £POA+VAT
The EnviroCell is a modular electrospray source that exchanges for the standard electrospray source on the UHV4i deposition system. The main difference between the EnviroCell and our other source is that the electrospray interface is contained within an inert gas (nitrogen) environmental chamber. This has 2 key advantages: firstly, the solvent and solute is contained within the system and is either extracted into the UHV4i system or flushed through the inert gas exhaust without entering the lab environment. This opens the possibility for the controlled use of otherwise harmful solvents or potentially toxic solutes. Second, , atmospheric contamination is minimized by controlling the gas environment around the electrospray interface. By replacing the atmosphere around the electrospray plume with clean nitrogen, airborne contaminants and oxygen are greatly reduced. The feedthrough flange of the EnviroCell has two gas inlet/outlet ports leading into the cell and a liquid port connecting to the emitter.
Figure 1. The Envirocell source fitted to the front end of the UHV4i electrospray deposition system, replacing the 5-axis manipulator and electrospray tee assembly.
Direct contact emitter
In the Envirocell source, the high voltage is delivered directly to the bare stainless steel electrospray emitter as opposed to the junction type contact of our standard source where the voltage is delivered into a liquid junction at the nexus of the liquid feed, the high voltage contact and the emitter. The direct contact geometry is more compact and allows the emitter to be contained in a small environmental chamber. The direct contact can also result in lower electrospray threshold voltages and is compatible with a larger range of liquid solvents as it does not rely on the conductivity of the solution.
Emitter positioning and viewing
The other significant difference between the standard electrospray interface of the UHV4i is that the EnviroCell source does not ultilise the 5-axis manipulator of the UHV4i. Instead, the emitter is rigidly mounted on the feedthrough flange of the EnviroCell itself. Emitter positioning is controlled instead by adjusting the small tilt angle of the flange relative to the body of the cell, which is achieved by adjusting the tightness of its 6 mounting bolts. The range of motion is significantly less than the 5-axis manipulator of the UHV4i, which is compensated by the use of highly symmetric emitters mounted precisely on the central axis of the cell. Optimisation of the emitter position is achieved in broadly the same way as on the UHV4i, but instead of adjusting the x, y and z translation stages, the user adjusts the tilt of the emitter by tightening the relevant bolt – almost as if you only used the pitch and yaw adjustment on the UHV4i after centering the emitter in x and y. Viewing the emitter-entrance interface is achieved via two glass windows and if necessary by opening the door on the side of the cell – each oriented 120 degrees from each other. The lightsource and microscope of the visualiser, when mounted, access the interface through the two windows.
Benefits and applications
The primary benefit of the EnviroCell is reducing atmospheric contamination from entering the deposition beam. For users concerned with the co-deposition of potential airborne contaminants the EnviroCell source offers an inert nitrogen atmosphere at the electrospray interface instead of air. Moreover, for molecules where the preferred solvent is potentially harmful, its containment within the cell can make these depositions viable. The trade-off is that emitter positioning in the cell is less intuitive than the standard 5-axis UHV4i manipulator and access to the emitter and entrance capillary for cleaning or replacement requires either opening the door of the cell, or the removal of the cell itself.
The Envirocell is intended for use with nitrogen as the inert gas at close to atmospheric pressure. Operating with gases having a lower dielectric strength than nitrogen, or at lower pressures could cause arcing of the emitter. If you have any questions about the feasibility of other configurations please get in touch.