How are scientists able to observe a single atom?

A “quantum microscope” sounds like an impossible device developed by some brilliant but possibly insane scientist who is working on a secret government project to inspect recently-discovered infinitesimal evidence from a decades-old conspiracy. Putting the science fiction aside, though, in May 2013, physicists were able to develop a quantum microscope that directly observed the electron orbitals of a hydrogen atom, a revolutionary step in quantum theory.

The problem is the wave function component of an electron’s behavior that it is incredibly difficult to observe. Previously, any direct observation of the wave function would destroy it before it could be fully observed. The quantum microscope, though, can directly magnify the microscopic state of a quantum particle to the laboratory scale in such a way that some quantum properties can be observed.

The quantum microscope utilizes photoionization microscopy to acquire the nodal structure of the electronic orbital of a hydrogen atom. This was performed by Aneta Stodolna, of the FOM Institute for Atomic and Molecular Physics in the Netherlands, with Marc Vrakking at the Max-Born-Institute in Berlin, Germany and other colleagues in Europe and the US.

In this experiment, a hydrogen atom is placed in an electric field and is excited by laser pulses. The excited electron then escapes from the atom and follows a trajectory to a dual microchannel plate detector perpendicular to the electric field. Since there are numerous trajectories that may reach that same point on the detector, the interference patterns created by the phase differences between these trajectories were observed, which were then magnified by more than 20,000x using an electrostatic zoom lens that would not disrupt the quantum coherence. The interference pattern observed revealed the structure of the wave function (Commissariat).

After all that scientific jargon, the question arises “What’s the point of doing this? Why do we need to know more about atoms?” The invention of the quantum microscope, though, has an incredible wealth of potential for the development of atomic and molecular-scale technologies in quantum mechanics. Quantum mechanics has applications in energy conversion at the molecular level, advancements in lasers – which are used in everything from CDs to missiles, ultraprecision in objects such as thermometers and atomic clocks, and instantaneous communication (Atteberry). By increasing our knowledge of objects at the atomic and subatomic level, these real-world applications can be explored to enhance our current technologies to their maximum potential. Edited from: How are scientists able to observe a single atom?

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