Revisions to an existing S/TEM system may set new standards for ultra-high resolution microscopy systems.

According to Dominique Hubert, VP and general manager of the Nanoresearch Division of FEI Co., Hillsboro, Ore., the concept for the new Titan3 80-300 S/TEM (scanning/transmission electron microscope) “began with listening to leading scientists in the U.S. who articulated the need for these microscopes in the next 10 years.”

FEI’s new Titan3 is an S/TEM enclosed in its own research environment. Image: FEI Co.

The Titan3 is FEI’s leading platform for sub-Angstrom study. Aberration-correction features (specifically, two optical correctors and a monochromator) that were formerly only available as add-ons are now packaged together for the first time. The entire instrument itself is enclosed in its own research environment.

“The new philosophy with Titan3 is about not only having three aberration correction components with full-remote operation, but also, importantly, having an enclosure that allows customers to relax on room requirements,” says Hubert. “The core theme of Titan is to allow a lot of room for manipulation and sample treatment.”

The new Titan is targeted to researchers who need to characterize the atomic-scale structure, chemistry, and dynamics of individual nanostructures. These researchers need access to both scanning modes and flexible sampling methods such as cryogenic TEM. The Titan3 can be operated in the range of 80 to 300 kV for optimized imaging of a wide variety of materials from ultra-light carbon compounds to ultra-dense heavy metal samples. But, as its name suggests, the Titan3 depends on its custom enclosure for optimum performance.

Thinking in the box

The Titan3’s enclosure is intended to limit acoustic, vibration, and heat factors. Its base provides stable support for a column with both image and probe correctors and a monochromator. Supplied with built-in power and electronics to provide atmospheric control, the Titan3 meets current refrigeration standards of the American Society of Heating, Refrigeration and Air-Conditioning Engineers under ASHRAE-15. Acoustical throughput is dampened by 20 dB. Hamish Fraser, director of the Center for the Accelerated Maturation of Materials (CAMM) at Ohio State Univ., Columbus, says, “The use of our Titan3 often involves numbers of students and post-doctoral fellows grouped around the console. Their often-loud talking and movements in the vicinity of the enclosed microscope appear to have no effect on the quality of the data produced.” Furthermore, Fraser says the microscope is situated in an old building in a room of reasonable quality, but, “the addition of the ‘box’—the Titan3’s newly designed base—provides excellent insulation and raises the quality of the system’s operating environment to being superb.”

Capitalizing on a new shape

In addition to the insulating benefits of Titan3’s outer casing, the column’s stiffness has been uprated by increasing its diameter to 300 mm. To prevent damping during information transfer because of alignment aberrations, a system was invented that automatically aligns optical components in the column during the microscope’s assembly stage.

The microscope also incorporates design requirements set forward by the Transmission Electron Aberration-corrected Microscope (TEAM) project, which has been organized by the U.S. Dept. of Energy to address chromatic aberration correction standards. One such improvement is the addition of at least two coils per lens to maintain constant temperature and prevent changes in magnetic flux from affecting correction efficiency.

In addition to coherent compensation, TEMs and S/TEMs must account for incoherent disturbances and the Titan3 is no exception. The energy spread of the electron beam, which is the source illumination, dampens contrast transfers at high spatial frequencies. A monochromator is used to overcome this problem because it selects the actual energy spread.

Another benefit of incorporating the correctors, says Hubert, is that FEI’s developers were able to open up the pole piece in comparison to other electron microscopes on the market. A side effect to ensuring that high stability is maintained in power, electronics, and environmental conditions is that the rest of the microscope is less dependent on environmental conditions. A larger pole piece gap is then possible, which improves the information limit and allows tomography and 3-D imaging to be done more easily.

Meeting researcher’s needs, FEI believes, will require a stable system that balances performance with a microscope that’s user-friendly and accessible to a wider range of disciplines. The Titan3 is at the vanguard of that effort.

—Paul Livingstone
—Adria Nieswand

Resources
• FEI Company, Hillsboro, Ore., 503-726-7500, www.fei.com