Microcontroller design for solution-phase molecular deposition in vacuum via a pulsed-solenoid valve

Abstract

A microcontroller was used to operate a pulsed-solenoid valve connected directly to a vacuum chamber (10−8mbar) to deposit microliters of solution resulting in monolayer and submonolayer coverage of the substrate. This technique is particularly suited for preparing samples to be characterized by scanning tunneling microscopy or atomic force microscopy. The microcontroller can be programed to open the valve at the millisecond timescale. The valve is particularly suited to deliver air and temperature sensitive molecules to the substrate without the need to remove the substrate from vacuum for deposition.

Light‐induced Photoswitching of 4‐(Phenylazo)benzoic Acid on Au(111)

“…[23] An advantage of this method is the ability to combine solution-based chemistry with ultra-high vacuum (UHV) studies, in which every component present in the sample solution is deposited on an atomically flat substrate. [24] During pulse deposition, molecules engage in non-equilibrium selforganization, which produces several kinetically trapped metastable states as opposed to a single thermodynamically favored structure. [25] Herein, this paper reports the photoswitching of 4-(phenylazo)benzoic acid or PABA (Figure 1) deposited on a Au(111) surface via a pulse solenoid valve.…”

Synthesis of extended covalently bound porphyrins on the Au(111) surface

“…In conclusion, TBrPP dissolved in DCM was pulse deposited onto the Au(111) surface via the pulse deposition valve. 50 TBrPP molecules were observed to tightly pack on the surface following the Au(111) herringbone reconstruction pattern. The fine interplay between the molecule–molecule and the molecule–substrate interactions that govern the self-assembly of the TBrPP molecules on the surface was elucidated.…”

Self-assembly controlled at the level of individual functional groups

“…This is achieved through pulse deposition, in which a pulsed-solenoid valve is used to spray microliter droplets directly into vacuum and onto the surface. 16 The solvent rapidly evaporates and the molecules are kinetically trapped in energy minima. Even for small and simple molecules, pulse deposition typically results in several co-existing structures.…”