Manufacturing Bits: March 11

Measuring molecules; fast coherent imaging; fiber lasers.


Measuring molecules
The Technical University of Munich (TUM) has developed a new metrology technique that determines the properties of individual molecules.

The technique, called single-molecule excitation–emission spectroscopy, improves upon the traditional methods to explore molecules. The traditional method, dubbed single-molecule spectroscopy (SMS), is not new and is used to analyze fluorescent mixtures of single molecules.

Prof. Dr. Juergen Hauer (left) and first author Erling Thyrhaug with their measuring instrument. In the background, spectra taken with it. (Image: A. Battenberg / TUM)

Traditionally, single-molecule detection methods are based on “fixed-wavelength excitation of individual molecules combined with dispersed detection of emission,” according to researchers from TUM in the Proceedings of the National Academy of Sciences of the United States of America, a scientific journal. These systems provide a view of individual emitter properties, but imaging single emitters remains challenging.

In response, researchers developed a new technique–single-molecule excitation–emission spectroscopy. This technology can be used for biological complexes and materials. For example, it will help identify molecules for future solar cells.

The new technology obtains data for ground- and excited states of molecules using a interferometer, according to TUM. For this, a interferometer and broadband technologies are added to a standard SMS microscope. Interferometers make measurements using two or more sources of electromagnetic waves. The waves are projected in a system and then superimposed. Then, the interference pattern is measured and analyzed.

TUM’s technology operates in a similar fashion with a twist. “It generates a double laser pulse with a controlled delay in between. The second pulse modulates the emission spectrum in a specific manner, which in turn provides information about the absorption spectrum. This information is then evaluated using a Fourier transformation,” according to TUM.

“Previously, emission spectra could be routinely acquired, but absorption measurements on individual molecules were extremely expensive,” said Jürgen Hauer, a professor of chemistry at TUM. “We have now attained the ultimate limit of detectability. The primary advantage is that we can, with little effort, transform a conventional measurement setup for acquiring emission spectra into a device for measuring emission and absorption spectra.”

Fast coherent imaging
Imec and KMLabs have announce a joint development effort to create an imaging and interference lithography laboratory.

The lab, called the attolab, will leverage KMLabs’ high-resolution, time-resolved coherent imaging technology. The lab will enable the characterization of complex materials and processes, such as photoresist radiation chemistry, two-dimensional materials and quantum materials. The technology will help gain insights into resists for extreme ultraviolet (EUV) lithography.

KMLabs develops compact advanced lasers and systems for research and industrial applications. One of those technologies is called XUUS, which is a coherent EUV/X-ray light source based on high-harmonic generation (HHG). HHG converts infrared or visible light into X-rays. In operation, a femtosecond laser beam hits a gas target. This, in turn, causes the conversion process.

The technology is a form of ptychographic coherent X-ray imaging. This imaging technique uses computer calculations and reconstruction algorithms to form 3D images of a sample.

KMLabs’ technology will allow the characterization of the molecular and quantum dynamics of materials within the attosecond to picosecond time regime. An attosecond is one quintillionth of a second.

This is key for understanding EUV sub-picosecond exposure processes. The technology will also play a key role in a next-generation EUV technology called high numerical aperture (NA) EUV. It will enable the study of EUV photon absorption and subsequent ionization processes at timescales from attoseconds to picoseconds.

The new laboratory will be equipped with multiple KMLabs EUV beamlines, providing the platform for a jointly developed series of EUV end stations. “Stochastic defectivity, resist photochemistry, and novel electronic materials development are all critical to the next generation of semiconductor enablement,” said Kevin Fahey, chief executive of KMLabs.

“Bringing this high-NA exposure and attosecond analytic capability to Imec’s 300mm cleanroom will enable unprecedented fundamental learning, significantly speeding up cycles of learning, and positively impacting the semiconductor technology roadmap in many critical domains,” said Greg McIntyre, director of advanced patterning at Imec.

Fiber lasers
KMLabs has developed a new ultrafast fiber laser technology for two-photon microscopy applications.

The technology, called Y-Fi NOPA, is a wavelength-tunable source from 650nm to 1020nm. This in turn covers a wide range of fluorophores.

Two-photon microscopy enables deep image acquisition in structures. Y-Fi NOPA enables better two-photon results. Y-Fi NOPA can be used for applications, including neuroscience, cancer research, immunology and developmental biology.

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